Utility of Acupuncture Therapy for Adult Chronic Daily Headache Prophylaxis: A Systematic Review and Meta-Analysis

Introduction

Chronic daily headache (CDH) is a collective term for a group of neurological disorders defined by headache episodes occurring on 15 or more days per month for a minimum of 3 consecutive months [1]. Approximately 4% to 5% of adults worldwide have CDH, with a markedly higher prevalence reported in females. CDH induces significant impairments in patients’ health-related quality of life, daily functional capacity, and socioeconomic productivity [2–6]. CDH is broadly classified into primary and secondary subtypes. Primary CDH encompasses chronic migraine (CM), chronic tension-type headache (CTTH), new daily persistent headache (NDPH), and persistent hemicrania continua. Secondary CDH is frequently associated with traumatic brain injury or medication overuse [7]. The pathophysiological mechanisms underlying CDH remain incompletely elucidated, with potential involvement of multiple factors, including central sensitization and dysregulation of neuromodulatory systems [8–11].

Significant advances have been made in headache medicine in recent years, with targeted therapies including botulinum toxin and calcitonin gene-related peptide (CGRP) inhibitors approved for the prevention of CM. OnabotulinumtoxinA, administered via intramuscular injection in the head and neck region, has been shown to reduce the frequency of headache days, alleviate headache severity, and improve migraine-related disability [12]. Its clinical efficacy is variable, and it can induce transient adverse events, including localized muscular weakness and pain at the injection site. Furthermore, CGRP pathway inhibitors, including the monoclonal antibodies erenumab, fremanezumab, galcanezumab, and eptinezumab, exert prophylactic effects by blocking CGRP or its cognate receptors, thereby inhibiting the biological activity of the CGRP pathway, and have demonstrated favorable safety and tolerability profiles [13]. However, these biologic agents are associated with high costs, have limited availability in most clinical healthcare settings, and warrant additional accumulation of long-term safety data and sustained efficacy evidence. This clinical scenario highlights the need for the development of cost-effective therapeutic interventions.

As a refractory headache disorder, CDH poses substantial challenges to clinical comprehensive management. Current pharmacological interventions yield limited remission rates, are associated with frequent adverse events, and carry persistent risks of drug dependence and medication overuse headache [14]. When experiencing prolonged disease duration and treatment resistance, patients with CDH frequently seek medical care, use polypharmacy, and undergo repeated hospitalizations, which imposes substantial burdens on individual healthcare expenditure and societal economic systems [15,16]. Consequently, clinical practice is in urgent need of non-pharmacological intervention strategies that are more widely accessible, well-tolerated, and suitable for long-term clinical application. Acupuncture, a relatively safe traditional Chinese medicine (TCM) therapeutic intervention, has received growing attention in the clinical management of headache disorders. Although numerous studies have investigated the efficacy of acupuncture for headache disorders, research specifically focused on CDH remains limited [17]. Prior systematic reviews have frequently failed to distinguish between chronic and episodic headache subtypes, lacked subgroup analyses that compare different acupuncture treatment protocols [18–20], and rarely evaluated the maintenance of long-term clinical efficacy in patients with CDH. These critical knowledge gaps impede the standardized integration of acupuncture into clinical CDH management algorithms.

The primary objective of this study is to systematically evaluate the short-term and sustained therapeutic effects of acupuncture in patients with CDH. Utilizing a rigorous follow-up study design, this research aims to generate high-quality clinical evidence to support the development of acupuncture-based prophylactic strategies for CDH, thereby informing the design of future targeted randomized controlled trials (RCTs) and guiding clinical practice.

Material and Methods

DATA SOURCES AND SEARCH STRATEGY:

Systematic searches were performed across multiple databases, including PubMed, EMBASE, the Cochrane Library, CNKI, VIP, SinoMed, and Wanfang Data, to identify RCTs evaluating acupuncture for the prophylaxis of CDH in adult patients. The search strategy incorporated keywords and Medical Subject Headings (MeSH) terms related to “acupuncture”, “chronic daily headache”, “chronic tension-type headache”, “chronic migraine”, and “randomized controlled trial”. The search strategy of PubMed is provided in Table 1. Additionally, supplementary data were retrieved by reviewing reference lists of relevant studies, clinical guidelines, conference abstracts, and trial registries.

INCLUSION AND EXCLUSION CRITERIA:

The inclusion criteria were as follows. (1) Study design: Studies were randomized controlled trials. (2) Study population: Patients were adults aged 18 years or older, with no restrictions on sex, ethnicity, disease duration, severity, or recruitment source. Participants had CDH diagnosed according to domestic or international criteria and had a baseline headache frequency of 15 or more episodes per month or 15 or more headache days per month. (3) Interventions: The intervention group received acupuncture alone or acupuncture combined with medication, with consistent baseline medication use across studies; no restrictions were placed on acupoint selection, manipulation techniques, needle retention time, or treatment duration. The control group received proven effective oral medication or sham acupuncture. (4) Outcomes: Studies were required to report at least 1 primary outcome, including headache frequency (episodes per month or per 4 weeks), headache days (days per month or per 4 weeks), headache intensity measured using the visual analog scale or numerical rating scale (0 indicating no pain and 10 indicating the most severe pain), or headache duration (hours per episode or hours per month). Secondary outcomes included analgesic use and adverse events. (5) Language: Only articles published in Chinese or English were included.

The exclusion criteria were as follows: (1) non-randomized controlled trials, including literature reviews, conference proceedings, clinical experience reports, case reports, animal studies, and retrospective studies; (2) evaluations of randomized controlled trials on acupuncture for acute attacks of CDH; (3) trials in which the intervention group combined acupuncture with drugs or other non-pharmacological therapies lacking conclusive efficacy evidence; the control group used drugs lacking conclusive efficacy evidence or unconventional drugs; or the intervention and control groups used different acupuncture protocols; (4) studies that did not report the outcome measures specified in the inclusion criteria or lacked available valid data; and (5) duplicate studies (only the most comprehensive or latest version was retained) or studies with unavailable full texts.

DATA EXTRACTION AND QUALITY ASSESSMENT:

Two reviewers independently screened studies, extracted data, and assessed methodological quality using the Cochrane risk of bias tool. Extracted data included study characteristics (eg, authors, publication year, sample size), participant demographics, intervention and control strategies, and outcome variables. Primary outcomes included headache frequency, headache days, headache intensity, and headache duration; secondary outcomes included usage of analgesics and adverse events. Disagreements between the 2 reviewers were resolved by a third reviewer.

CERTAINTY OF EVIDENCE ASSESSMENT:

Two researchers independently evaluated the certainty of evidence for each outcome using the GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) approach; disagreements were resolved by a third researcher. This approach is the recommended tool for assessing evidence quality in systematic reviews of RCTs. The GRADE system classifies evidence quality into 4 levels: high, moderate, low, and very low. In RCTs, the initial evidence grade is high; however, a comprehensive assessment of 5 factors that can reduce evidence quality – risk of bias, inconsistency, indirectness, imprecision, and publication bias – is required to determine the final evidence grade.

STATISTICAL ANALYSIS:

Meta-analyses were performed using Review Manager 5.4 and Stata 17. For continuous variables, standardized mean differences (SMDs) with 95% confidence intervals (CIs) were used, as the included studies utilized different scales to assess outcomes. Heterogeneity among studies was evaluated using the chi-square test and I² statistic: if P>0.10 and I²<50%, heterogeneity was considered not statistically significant, and a fixed-effects model was used; if P≤0.10 or I²≥50%, substantial heterogeneity was identified, and a random-effects model was applied. Sensitivity analyses were performed by sequentially excluding individual studies to examine changes in effect sizes, which allowed for assessment of the robustness of the pooled results. When data permitted, subgroup analyses were conducted based on treatment modality, CDH subtype, and treatment duration to identify potential sources of heterogeneity. Additionally, funnel plots were generated to evaluate publication bias for outcomes with 10 or more RCTs.

Results

LITERATURE SCREENING AND INCLUDED STUDIES:

Following a systematic search of Chinese and English databases, 2214 relevant records were initially identified. After excluding 815 duplicate records, 1399 articles advanced to the title and abstract screening phase. At this phase, 1246 studies were excluded due to mismatches in research topic, study type, target population, or intervention strategies. Subsequently, full-text evaluation was performed on the remaining 153 articles. Of these, 131 were excluded for the following reasons: CTs or quasi-RCTs (n=7), failure to meet the inclusion criteria (n=37), inappropriate interventions (n=13), mismatched control strategies (n=23), incompatible outcome measures (n=13), incomplete or unavailable data (n=36), and duplicate publications (n=2). Ultimately, 22 RCTs [22–43] were included in this meta-analysis. The full literature screening process is detailed in the PRISMA flow diagram (Figure 1).

CHARACTERISTICS OF INCLUDED STUDIES:

This meta-analysis included 22 RCTs involving 1449 patients with CDH. The experimental groups received either acupuncture alone or acupuncture combined with guideline-recommended Western drugs, whereas the control groups received either guideline-recommended Western drugs or sham acupuncture. Sample sizes across the included studies ranged from 34 to 218 participants. The majority of studies were conducted in China, with a smaller number conducted in Germany, Iran, Turkey, Denmark, Russia, and other countries. Additionally, 2 studies [24,42] were multi-arm RCTs with a shared control group (incorporating multiple interventions). In accordance with the Cochrane Handbook for Systematic Reviews of Interventions, these trials were split into 2-arm studies (eg, Wu2022a, Wu2022b), with balanced sample sizes in the control and experimental groups (Table 2).

Overall, most studies had a low risk of bias in the domains of incomplete outcome data and selective reporting, with the majority providing sufficient follow-up and detailed reporting protocols. Specifically, all 22 studies were assessed as having a low risk of other biases, selective reporting, and incomplete outcome data. Regarding random sequence generation, 16 studies were assessed as having a low risk, while the remaining 6 studies [31,33,35,40–42] were assessed as having an unclear risk, owing to insufficient details on randomization methods. For allocation concealment, 7 studies [27,28,30,32,34,38,39] were assessed as having a low risk because they used concealment methods (eg, opaque sealed envelopes, third-party allocation); 2 studies [26,29] were also assessed as having a low risk, despite only mentioning allocation concealment without specifying the methods used. An additional 13 studies did not report any allocation concealment methods and were assessed as having an unclear risk. Regarding blinding: (1) 7 studies [29,30,32,34,37,39,43] implemented patient-only single-blinding and were assessed as having a high risk of bias; (2) 3 studies [33,35,41] implemented double-blinding (for both patients and investigators) and were assessed as having a low risk of bias; (3) the remaining 12 studies did not report blinding and were assessed as having an unclear risk of bias. Eight studies [27,28,30,32–34,38,39] implemented outcome assessor blinding, whereas the remaining 14 studies did not report this detail (Figure 2).

HEADACHE FREQUENCY: Nine studies involving 398 adults with CDH (acupuncture group: 199; control group: 199) were included to evaluate the effect of acupuncture on post-treatment headache frequency. A fixed-effects model was applied due to low heterogeneity (I2=1%; P=0.42). Results showed a significantly lower headache frequency in the acupuncture group than in the control group (SMD=−0.32, 95% CI [−0.52, −0.12]; P=0.001; Figure 3A).

Three studies involving 202 participants (acupuncture group: 102; control group: 100) were included to assess headache frequency during follow-up. Due to moderate heterogeneity (I2=62%; P=0.07), a random-effects model was applied. A trend toward a significant difference was observed between the 2 groups, but this difference did not reach statistical significance (SMD=−0.47, 95% CI [−0.94, 0.00]; P=0.05; Figure 4A).

HEADACHE DAYS: Twelve studies involving 826 adults with CDH (acupuncture group: 420; control group: 406) reported headache days following treatment. Due to moderate heterogeneity (I2=59%; P=0.004), a random-effects model was applied. Results showed a significantly lower number of headache days in the acupuncture group than in the control group (SMD=−0.72, 95% CI [−0.96, −0.48]; P<0.00001; Figure 3B).

Eight studies involving 595 adults with CDH (acupuncture group: 302; control group: 293) were included to assess monthly headache days during follow-up. Moderate heterogeneity was present (I2=52%; P<0.00001). Results indicated that the reduction in headache days following acupuncture treatment persisted throughout the follow-up period (SMD=−0.70, 95% CI [−0.96, −0.43]; P<0.00001; Figure 4B).

HEADACHE INTENSITY: Seventeen studies involving 1091 patients with CDH (acupuncture group: 549; control group: 542) were included to assess headache intensity following treatment. Due to high heterogeneity (I2=89%; P<0.00001), a random-effects model was applied. Results showed a significant reduction in headache intensity in the acupuncture group (SMD=−0.63, 95% CI [−1.01, −0.26]; P=0.0010; Figure 3C).

Eight studies involving 564 adults with CDH (acupuncture group: 285; control group: 279) were included to assess headache intensity during follow-up. High heterogeneity (I2=94%; P<0.00001) necessitated the application of a random-effects model. Results indicated that acupuncture’s effect on reducing headache intensity persisted throughout the follow-up period (SMD=−1.11, 95% CI [−1.93, −0.29]; P=0.008; Figure 4C).

HEADACHE DURATION:

Nine studies involving 525 patients with CDH (acupuncture group: 267; control group: 258) reported headache duration following treatment. Due to high heterogeneity (I2=90%; P<0.00001), a random-effects model was applied. Results showed a significant reduction in headache duration in the acupuncture group (SMD=−1.18, 95% CI [−1.77, −0.58]; P=0.0001; Figure 3D).

Five studies involving 293 participants with CDH (acupuncture group: 150; control group: 143) were included to assess headache duration during follow-up. Due to high heterogeneity (I2=94%, P<0.00001), a random-effects model was applied. Results indicated that acupuncture’s effect on reducing headache episode duration persisted throughout the follow-up period (SMD=−1.83, 95% CI [−3.02, −0.64]; P=0.003; Figure 4D).

USAGE OF ANALGESICS: Nine studies involving 431 patients with CDH (acupuncture group: 219; control group: 212) reported post-treatment analgesic use. Heterogeneity was low (I2=46%, P=0.06), thus a fixed-effects model was applied. Results showed a significant reduction in analgesic use in the acupuncture group (SMD=−0.52; 95% CI [−0.71, −0.32]; P<0.00001; Figure 3E).

Six studies involving 305 participants with CDH (acupuncture group: 155; control group: 150) were included to assess acute analgesic use during follow-up. High heterogeneity (I2=72%; P=0.003) necessitated the application of a random-effects model. Results indicated that acupuncture’s effect on reducing analgesic use persisted throughout the follow-up period (SMD=−0.60, 95% CI [−1.05, −0.16]; P=0.007; Figure 4E).

ADVERSE EVENTS: Ten studies reported adverse events, with 3 studies [28,30,37] reporting no adverse events in the experimental group. Seven studies [26,27,29,36,38,41,43] collectively reported 12 cases of adverse events, primarily including: 1 case of indigestion, 2 cases of localized pain, 3 cases of subcutaneous hematoma, 1 case of needle phobia, 1 case of skin numbness, and 1 case of localized ecchymosis. One case lacked specific details on adverse events, and no serious adverse events were reported across all included studies. The overall incidence of adverse events in the acupuncture group was 2.1% (12/572). The remaining 12 studies did not report any adverse events.

SUBGROUP ANALYSES OF OUTCOME INDEX: To further explore differences in efficacy and potential factors influencing acupuncture for CDH management, a subgroup analysis was performed based on treatment modality, CDH subtype, treatment duration, and follow-up length (Table 3).

Regarding treatment modality, acupuncture demonstrated clear and statistically significant positive effects during the treatment period on headache frequency, headache days, headache intensity, headache duration, and analgesic use. Among these outcomes, the reduction in headache days exhibited the most reliable effect with low heterogeneity. During follow-up, most positive effects were maintained, although some indicators showed diminished efficacy or increased heterogeneity – with improvements in headache frequency potentially diminishing.

Regarding CDH subtypes, acupuncture demonstrated efficacy across all CDH subtypes (eg, CTTH, CM) during treatment, with patients with CM exhibiting particularly pronounced effects (moderate-to-large effect sizes) in headache days and headache duration. During follow-up, patients with CTTH demonstrated more sustained efficacy, with stable improvements across multiple indicators, suggesting acupuncture may exert longer-lasting regulatory effects on CTTH pathophysiological mechanisms. For patients with CM, only the reduction in headache days remained stable, with efficacy diminishing for other indicators. Due to insufficient data, results for unstratified CDH remained inconsistent.

Subgroup analysis by treatment duration revealed that therapy lasting 1 month or less demonstrated significant effects across all outcomes – headache days, headache intensity, headache duration, and analgesic use – often with the largest effect sizes, indicating acupuncture’s rapid onset of action. Improvements in headache days remained stable regardless of treatment duration. Notably, headache intensity and headache duration consistently showed a trend favoring treatment of 1 month or less over 1 to 2 month courses; for certain indicators, efficacy even diminished during follow-up. Short-term intensive treatment should be prioritized for rapid alleviation of headache severity and duration. However, considerable heterogeneity suggests other significant factors influence outcomes, necessitating cautious interpretation.

Subgroup analysis of follow-up data by length revealed that acupuncture efficacy diminishes over time. Prophylactic effects (reduction in headache days) proved most enduring, remaining effective beyond 3 months; symptomatic effects (intensity reduction, analgesic use reduction, and duration shortening) showed no significant benefit beyond 3 months, warranting consideration of consolidation therapy. Evidence for headache frequency reduction at 3 months or less was marginally significant, with insufficient long-term data.

SENSITIVITY ANALYSIS, PUBLICATION BIAS, AND EVIDENCE CERTAINTY: Sensitivity analyses were performed for all 5 outcomes after treatment and during follow-up. Sequential exclusion of individual studies did not substantially change the pooled effect size or the direction of results, indicating the robustness of the pooled results, which were not influenced by any single study. For outcomes with 10 or more RCTs (ie, headache days and headache intensity), funnel plots were generated to evaluate publication bias. These plots exhibited significant asymmetry, which strongly suggested the presence of publication bias; thus, the findings for these outcomes require cautious interpretation (Figure 5). The certainty of evidence for the 5 outcomes was evaluated using the GRADE approach and classified as moderate, primarily due to the presence of bias risk and heterogeneity among the included trials (Tables 4, 5).

Discussion

PRIMARY FINDINGS:

This meta-analysis of 22 RCTs involving 1449 patients with CDH demonstrates that acupuncture provides meaningful therapeutic benefits for the prophylaxis of CDH. Specifically, patients in the acupuncture group exhibited significant reductions in headache frequency and headache days – alleviating their chronic headache burden and supporting a return to daily functioning – as well as a marked decrease in analgesic use. This not only lowers the risk of drug-related adverse events, such as gastrointestinal injury, hepatotoxicity, and nephrotoxicity, but also reduces the risk of medication dependence – rendering acupuncture particularly suitable for the long-term management of CDH. However, substantial heterogeneity was observed for outcomes, including headache intensity and episode duration, which highlights the need for cautious interpretation of these results. Furthermore, only 10 studies reported adverse events – all of which were mild – and no serious adverse events were reported across any included study, confirming that acupuncture is a low-risk intervention for CDH. Moreover, the beneficial effects on key outcomes (eg, headache days, analgesic use) were sustained during post-treatment follow-up, which is consistent with findings from Linde et al [44]. Subgroup analyses revealed consistent efficacy across CDH subtypes (CM and CTTH), treatment durations (4–12 weeks), and intervention strategies (acupuncture alone or combined with medication), indicating broad clinical applicability.

COMPARISON WITH PREVIOUS STUDIES:

The findings of this study are broadly consistent with previous research; however, this is the first meta-analysis to explicitly focus on CDH, whereas prior studies predominantly focused on episodic or mixed headache disorders. This work fills a critical gap in the literature on acupuncture for CDH prophylaxis, extending the established utility of acupuncture from episodic headaches to CDH and providing targeted evidence for patients with refractory CDH-related chronic pain.

The 2022 Chinese Guidelines for the Prevention and Treatment of Migraine [45] recommend acupuncture for headache prophylaxis, and multiple meta-analyses [44,46,47] have shown that acupuncture is comparable to, or more effective than, standard medications, including beta-blockers, calcium channel blockers, and antiepileptics, while exhibiting a more favorable safety profile. The present study builds on this by demonstrating that acupuncture outperforms conventional medications across all key outcomes except headache intensity, a finding of particular relevance for CDH, as patients urgently require long-term reductions in headache days and decreased medication reliance.

Notably, previous network meta-analyses on migraine [48] and tension-type headache [49] have shown that acupuncture combined with medication is more effective than medication alone in reducing headache duration and pain intensity assessed by the visual analog scale. In contrast, the subgroup of patients with CDH receiving acupuncture plus conventional medication in this study did not show additional benefits, with headache intensity and analgesic use comparable between the combined and medication-only groups. This discrepancy may be attributed to 2 key factors: (1) the inherent differences between headache types, as CDH is a chronic daily disorder, whereas episodic headaches are intermittent, with distinct pathophysiological mechanisms and disease burdens; (2) differences in intervention design, as acupuncture in this study was administered for only 4 weeks, with standard medication doses maintained throughout, which may have been insufficient to fully elicit the synergistic effects of combined therapy in patients with CDH. This suggests that combined treatment protocols for CDH require further optimization.

Controversy remains regarding whether the efficacy of acupuncture observed in prior studies is primarily mediated by placebo effects. Multiple large-scale clinical trials [50–53] have shown no clinically meaningful difference, or only a minimal difference, in prophylactic efficacy between verum acupuncture and sham acupuncture. In contrast, the acupuncture vs sham acupuncture subgroup in this study exhibited a significant reduction in monthly headache days, indicating that the efficacy of acupuncture is not solely dependent on placebo mechanisms. This finding is consistent with results from Sun et al [54], refining previous debates and providing stronger support for acupuncture’s specific therapeutic effects.

POSSIBLE MECHANISTIC EXPLANATIONS:

The trigeminal neurovascular theory is widely accepted as a key framework for understanding the pathogenesis of CDH. Acupuncture has been shown to reduce the number of meningeal mast cells and macrophages, downregulate pro-inflammatory cytokines (eg, IL-1β, IL-6, TNF-α), and alleviate peripheral inflammation, effects thought to be mediated by improving migraine-related pain sensitization, modulating neurotransmitter levels, and regulating inflammatory factor expression [55]. It also modulates the NF-κB signaling pathway to balance immune responses and reduce abnormal activation of pain transmission pathways induced by neuroinflammation, thereby inhibiting the progression of neurogenic inflammation [56].

Acupuncture specifically downregulates CGRP levels in the trigeminal ganglion and ascending vascular pathways [57,58], blocking pain amplification effects in a manner consistent with the clinical rationale for CGRP-targeted migraine therapies. It also bidirectionally regulates neurotransmitters: increasing serum 5-HT levels, reducing substance P concentrations, and balancing glutamate-to-GABA ratios to inhibit neuronal hyperexcitability, thus blocking pain signal transmission at its source [59,60].

Additionally, acupuncture modulates levels of vasoactive substances, reducing the vasoconstrictors endothelin-1 and thromboxane B2, while increasing the vasodilators nitric oxide and 6-K-PGF1α, correcting cerebral vasomotor dysregulation [61,62]. This simultaneously increases cerebral blood flow, ameliorating cerebral ischemia and hypoxia, and reducing headaches induced by vasospasm or vasodilation, directly intervening in vascular dysfunction within the trigeminal vascular system.

For CTTH specifically, acupuncture directly relieves myofascial tension and alleviates cranial muscle spasm, improving local ischemia and reducing the accumulation of pain-inducing substances. This mitigates local inflammation and peripheral nerve hypersensitivity, interrupting the vicious cycle of “myofascial injury to central sensitization in the trigeminal nucleus to exacerbated headache”. Acupuncture also modulates neurotransmitters such as 5-HT and dopamine via “spirit-regulating” and “liver-soothing” techniques or stimulation of emotion-related brain regions [63,64], improving mental health and indirectly alleviating emotion-triggered headaches.

STRENGTHS AND LIMITATIONS:

A key strength of this study is that it is the first meta-analysis to rigorously adhere to PRISMA guidelines and include data from both the treatment and follow-up phases, with the goal of evaluating acupuncture’s role in improving key CDH-related outcomes. The reliability of its conclusions is enhanced by comprehensive subgroup analyses (stratified by headache subtype, treatment modality, and treatment duration), supported by sensitivity analyses and rigorous quality assessments.

This study also has several limitations. (1) Blinding is inherently challenging to implement in acupuncture trials, as the physical nature of acupuncture makes double-blinding difficult to achieve; this can introduce bias from placebo effects or patient expectations. (2) Most outcome measures rely on subjective patient-reported data (eg, questionnaires), which can introduce recall bias [65]. (3) Acupuncture protocols are not standardized, with significant variability in acupoint selection, needle retention time, and treatment frequency; further, sample sizes are generally small, and variables such as practitioner expertise, needle insertion depth, and patients’ perception of “de qi” (needle sensation) remain uncontrolled. (4) Publication bias was observed for key outcomes (eg, headache days and headache intensity), and while systematic searches of Chinese and English databases were conducted, language-related bias may persist. (5) ICHD-3 [66] no longer classifies CDH as an independent entity but subdivides it into specific headache types; this led to inconsistent patient classification across included studies, introducing classification bias. Although subgroup analyses were stratified by CDH subtype, the number of eligible studies for each subtype remains limited.

FUTURE RESEARCH DIRECTIONS:

Evidence from this meta-analysis demonstrates that acupuncture is an effective and safe preventive intervention for CDH, resulting in significant reductions in headache frequency, headache days, and analgesic medication use. By addressing a key gap in the CDH literature and aligning the present findings with clinical management objectives, this study offers robust support for the integration of acupuncture into comprehensive, patient-centered care pathways for patients with CDH.

Future research should prioritize protocol optimization and mechanistic elucidation to inform the targeted clinical application of acupuncture in CDH management and should include large-scale, multiethnic, double-blind RCTs with rigorous diagnostic criteria, as well as larger sample sizes and extended follow-up periods. Standardization of outcome reporting for CDH, protocolization of acupuncture regimens, and rigorous control of efficacy-influencing variables, such as practitioner training and needle technique, are also essential. Further exploration of acupuncture’s mechanisms in CDH will provide more targeted clinical guidance for patients with distinct CDH subtypes.

Notably, the German Acupuncture Trial (GERAC) for episodic headache and CTTH showed no significant difference in efficacy between traditional Chinese medicine acupoints and non-traditional acupoints [67], suggesting limited influence of acupoint selection on clinical outcomes. In contrast, studies using acupressure or laser acupuncture argue that precise acupoint stimulation is critical for efficacy [68]. This controversy requires clarification through large-scale, well-designed RCTs.

Conclusions

A meta-analysis incorporating 22 randomized controlled trials confirmed that acupuncture demonstrates clear clinical value and sustained efficacy in preventing CDH in adults. Compared with control interventions, acupuncture significantly reduced headache frequency (MD=−0.32; P=0.001), number of headache days (MD=−0.72; P<0.00001), headache intensity (SMD=−0.63; P=0.001), and headache duration (SMD=−1.18; P=0.0001). It also reduced analgesic use (MD=−0.52; P<0.00001). These benefits remained significant during follow-up, with persistent significant reductions in headache days (SMD=−0.70; P<0.00001), headache intensity (SMD=−1.11; P=0.008), headache duration (SMD=−1.83; P=0.003), and analgesic use (SMD=−0.60; P=0.007), indicating sustained therapeutic effects of acupuncture.

Acupuncture demonstrated good safety, with only mild adverse events reported and no serious events, making it a well-tolerated non-pharmacological intervention. It is particularly suitable for CDH patients with medication intolerance, high risk of medication-overuse headaches, or preference for integrated treatment. Acupuncture can serve as a first- or second-line strategy for CDH prevention, offering significant value in reducing headache burden and lowering medication dependency.

Heterogeneity among studies suggests the need for individualized acupuncture protocols and rigorous efficacy monitoring in clinical practice. This review provides the first systematic evidence supporting acupuncture for CDH prevention. Future large-scale, rigorously designed randomized controlled trials employing standardized acupuncture protocols with long-term follow-up are required to further clarify its role in clinical guidelines.