, Pil-Wook Chung2
, Hong-Kyun Park3
, Mi Ji Lee4
, Jae Myun Chung5
, Kyung Min Kim6
, Jiyoung Kim7
, Heui-Soo Moon2
, Dae-Woong Bae8
, Jong-Hee Sohn9
, Tae-Jin Song10
, Wonwoo Lee11
, Soohyun Cho12
, Myoung-Jin Cha13
, Yun-Ju Choi14
, Miyoung Choi15
, The Clinical Practice Guideline Committee of the Korean Headache Society 1Department of Neurology, Ewha Womans University Mokdong Hospital, Ewha Womans University College of Medicine, Seoul, Republic of Korea
2Department of Neurology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
3Department of Neurology, Inje University Ilsan Paik Hospital, Inje University College of Medicine, Goyang, Republic of Korea
4Department of Neurology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Republic of Korea
5Department of Neurology, H Plus Yangji Hospital, Seoul, Republic of Korea
6Department of Neurology, Yonsei University College of Medicine, Seoul, Republic of Korea
7Department of Neurology, Pusan National University Hospital, Busan, Republic of Korea
8Lifelong Neurology Clinic, Dongtan, Republic of Korea
9Department of Neurology, Chuncheon Sacred Heart Hospital, Hallym University College of Medicine, Chuncheon, Republic of Korea
10Department of Neurology, Ewha Womans University Seoul Hospital, Ewha Womans University College of Medicine, Seoul, Republic of Korea
11Department of Neurology, Yongin Severance Hospital, Yonsei University College of Medicine, Yongin, Republic of Korea
12Department of Neurology, Uijeongbu Eulji Medical Center, Eulji University School of Medicine, Uijeongbu, Republic of Korea
13Department of Neurology, National Police Hospital, Seoul, Republic of Korea
14Dr. Choi’s Neurology Clinic, Jeonju, Republic of Korea
15Division Healthcare Research, National Evidence-based Healthcare Collaborating Agency, Seoul, Republic of Korea
© 2026 The Korean Headache Society
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (https://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
AVAILABILITY OF DATA AND MATERIAL
Not applicable.
AUTHOR CONTRIBUTIONS
Conceptualization: BSK, PWC, HKP, MJL, JMC, MC; Data curation: BSK, PWC, HKP, MJL, JMC, MC; Formal analysis: BSK, PWC, HKP, MJL, JMC, MC; Investigation: BSK, PWC, HKP, MJL, JMC, KMK, JK, HSM, DWB, JHS, TJS, WL, SC, MJC, YJC; Methodology: BSK, PWC, HKP, MJL, JMC, MC; Supervision: BSK, PWC, HKP, MJL, JMC, MC; Writing–original draft: BSK, PWC, HKP, MJL, JMC, KMK, JK, HSM, DWB, JHS, TJS, WL, SC, MJC, YJC; Writing–review & editing: BSK, PWC, HKP, MJL, JMC, MC.
CONFLICT OF INTEREST
Mi Ji Lee is the Associate Editor of Headache and Pain Research and was not involved in the review process of this article. All authors have no other conflicts of interest to declare.
FUNDING STATEMENT
None.
ACKNOWLEDGMENTS
None.
| Certainty assessment | No. of patients | Effect | Certainty | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| No. of studies | Study design | Risk of bias | Inconsistency | Indirectness | Imprecision | Other considerations | Triptan | Placebo | Relative (95% CI) | Absolute (95% CI) | |
| Subcutaneous sumatriptan for pain relief at 15 minutes | |||||||||||
| 2 | Randomized trials | Not serious | Not serious | Not serious | Serious* | None | 98/131 (74.8%) | 41/127 (32.3%) | Not estimable | ⨁⨁⨁◯ | |
| Moderate | |||||||||||
| Subcutaneous sumatriptan for pain-free status at 15 minutes | |||||||||||
| 2 | Randomized trials | Not serious | Not serious | Not serious | Serious† | None | 63/131 (48.1%) | 22/127 (17.3%) | Not estimable | ⨁⨁⨁◯ | |
| Moderate | |||||||||||
| Intranasal zolmitriptan for pain relief at 30 minutes | |||||||||||
| 2 | Randomized trials | Not serious | Not serious | Not serious | Serious* | None | 122/229 (53.3%) | 27/111 (24.3%) | Not estimable | ⨁⨁⨁◯ | |
| Moderate | |||||||||||
| Intranasal zolmitriptan for pain-free status at 30 minutes | |||||||||||
| 2 | Randomized trials | Not serious | Not serious | Not serious | Serious* | None | 92/229 (40.2%) | 20/111 (18.0%) | Not estimable | ⨁⨁⨁◯ | |
| Moderate | |||||||||||
| Intranasal sumatriptan pain response at 30minutes | |||||||||||
| 1 | Randomized trial | Not serious | Not serious | Not serious | Serious‡ | None | Five study centers enrolled 118 patients in whom 154 attacks were treated: 77 with sumatriptan and 77 with placebo. The response rates at 30 minutes were 57% for sumatriptan and 26% for placebo (p=0.002). The pain-free rates at 30 minutes were 47% for sumatriptan and 18% for placebo (p=0.003). | ⨁⨁⨁◯ | |||
| Moderate | |||||||||||
| Oral zolmitriptan for pain relief at 30 minutes | |||||||||||
| 1 | Randomized trial | Not serious | Not serious | Not serious | Serious§ | None | Zolmitrptan 10 mg produced significant pain relief at 30 minutes compared with placebo in patients with episodic headache (46.8% versus 28.9%; p=0.02). Zolmitriptan 5 mg in patients with episodic cluster headache was not significantly different from placebo. | ⨁⨁⨁◯ | |||
| Moderate | |||||||||||
GRADE, Grading of Recommendations Assessment; Development and Evaluation; CI, confidence interval.
*Two randomized controlled trials (RCTs) and small sample size;
†Study design flawed: allocation and random sequence generation;
‡Single RCT and small sample size;
§Single RCT and different effect among doses and headache type (episodic vs. chronic).
| Certainty assessment | Impact | Certainty | Importance | ||||||
|---|---|---|---|---|---|---|---|---|---|
| No. of studies | Study design | Risk of bias | Inconsistency | Indirectness | Imprecision | Other considerations | |||
| Pain-free status at 15 minutes | |||||||||
| 1 | Randomized trial | Not serious | Not serious | Not serious | Serious* | None | Fifty-seven patients with episodic cluster headache and 19 with chronic cluster headache were available for analysis. For the primary end point the difference between oxygen, 78% (95% CI, 71%–85% for 150 attacks) and air, 20% (95% CI, 14%–26%; for 148 attacks) was significant. | ⨁⨁⨁◯ | CRITICAL |
| Moderate | |||||||||
| Pain-free status at 30 minutes | |||||||||
| 1 | Randomized trial | Not serious | Not serious | Not serious | Serious* | None | 72% of oxygen-treated attacks and 24% of placebo-treated attacks were pain-free at 30 minutes. | ⨁⨁⨁◯ | IMPORTANT |
| Moderate | |||||||||
| Certainty assessment | Impact | Certainty | Importance | ||||||
|---|---|---|---|---|---|---|---|---|---|
| No. of studies | Study design | Risk of bias | Inconsistency | Indirectness | Imprecision | Other considerations | |||
| Percentages of patients with two or fewer attacks per day in the 2–4 days after the third injection | |||||||||
| 1 | Randomized trial | Not serious | Not serious | Not serious | Serious* | None | Forty-three patients (15 with chronic and 28 with episodic cluster headache) received cortivazol or placebo. Among the 21 patients who received cortivazol, 20 had a mean of two or fewer daily attacks after injections compared with 12 of 22 controls (odds ratio, 14.5; 95% CI, 1.8–116.9; p=0.012). | ⨁⨁⨁◯ | CRITICAL |
| Moderate | |||||||||
| Total number of attacks between day 1 and day 15 | |||||||||
| 1 | Randomized trial | Not serious | Not serious | Not serious | Serious* | None | Patients who received cortivazol also had fewer attacks (mean, 10.6; 95% CI, 1.4–19.9) in the first 15 days of the study than did controls (mean, 30.3; 95% CI, 21.4–39.3; mean difference, 19.7; 95% CI, 6.8–32.6; p=0.004). | ⨁⨁⨁◯ | IMPORTANT |
| Moderate | |||||||||
| Disappearance of attacks within 72 hours for the 1st week (sustained attack-free 72 hours to 1 week) | |||||||||
| 1 | Randomized trial | Serious† | Not serious | Not serious | Serious* | None | Thirteen patients were allocated to the steroid arm and 10 patients were allocated to the placebo arm. Eleven steroid group patients (85%) became attack-free in the first week after the injection compared to none in the placebo group (p=0.0001). | ⨁⨁◯◯ | CRITICAL |
| Low | |||||||||
| Certainty assessment | Impact | Certainty | Importance | ||||||
|---|---|---|---|---|---|---|---|---|---|
| No. of studies | Study design | Risk of bias | Inconsistency | Indirectness | Imprecision | Other considerations | |||
| Mean number of attacks within the first week of treatment | |||||||||
| 1 | Randomized trial | Not serious | Not serious | Not serious | Serious* | None | The mean number of attacks within the first week of treatment (day 1–7) was 7.1 (SD, 6.5) in the prednisone group compared with 9.5 (SD, 6.0; difference, –2,4; 95% CI, –4.8 to –0.03; p=0.002) in the placebo group. | ⨁⨁⨁◯ | CRITICAL |
| Moderate | |||||||||
| Number of cluster headache attacks after 28 days | |||||||||
| 1 | Randomized trial | Not serious | Not serious | Not serious | Serious* | None | The mean number of cluster headache attacks after 28 days in the prednisone group was still reduced compared with placebo: 15.6 (SD, 15.5) versus 20.2 (SD, 15.0) attacks (difference, –4.7; 95% CI, –11.0 to –1.7, p=0.0356). | ⨁⨁⨁◯ | IMPORTANT |
| Moderate | |||||||||
| 50% reduction in attack frequency at day 7 | |||||||||
| 1 | Randomized trial | Not serious | Not serious | Not serious | Serious* | None | At least a 50% reduction in attack frequency at day 7 was reported by 25 (49%) of 51 patients with prednisone treatment compared with eight (15%) of 55 patients with placebo. | ⨁⨁⨁◯ | IMPORTANT |
| Moderate | |||||||||
| Certainty assessment | Impact | Certainty | Importance | ||||||
|---|---|---|---|---|---|---|---|---|---|
| No. of studies | Study design | Risk of bias | Inconsistency | Indirectness | Imprecision | Other considerations | |||
| Percentage of the patients whose attacks were substantially improved in 1 week | |||||||||
| 1 | Randomized trial | Serious* | Not serious | Not serious | Serious† | None | Thirteen in the lithium group and 14 in the placebo group. | ⨁⨁◯◯ | IMPORTANT |
| Substantial improvement was reached in 62% of the lithium group and 43% of the placebo group. | Low | ||||||||
| Headache index reduction compared to verapamil in preventing chronic cluster headache | |||||||||
| 1 | Randomized trial | Serious* | Not serious | Serious‡ | Serious† | None | In a randomized crossover trial, both lithium and verapamil reduced headache index in chronic cluster headache, but verapamil had fewer adverse effects and a shorter latency of action. | ⨁◯◯◯ | CRITICAL |
| Very low | |||||||||
| Certainty assessment | Impact | Certainty | Importance | ||||||
|---|---|---|---|---|---|---|---|---|---|
| No. of studies | Study design | Risk of bias | Inconsistency | Indirectness | Imprecision | Other considerations | |||
| Reduced headache attack frequency | |||||||||
| 1 | Randomized trial | Serious* | Not serious | Not serious | Serious† | None | In the second week both the number of attacks (verapamil 0.6±0.88, placebo 1.65±1.01; p<0.001) and the consumption of analgesics (verapamil 0.5±0.87, placebo 1.2±1.03; p<0.004) were lower in the verapamil arm than the placebo arm. | ⨁⨁◯◯ | CRITICAL |
| Low | |||||||||
| Headache index reduction compared to lithium in preventing chronic cluster headache | |||||||||
| 1 | Randomized trial | Serious* | Not serious | Serious‡ | Serious† | None | In a randomized double-blind crossover trial, both lithium and verapamil reduced chronic cluster headache attacks, but verapamil was associated with fewer adverse effects and a shorter latency of action. | ⨁◯◯◯ | CRITICAL |
| Very low | |||||||||
| Certainty assessment | Impact | Certainty | Importance | ||||||
|---|---|---|---|---|---|---|---|---|---|
| No. of studies | Study design | Risk of bias | Inconsistency | Indirectness | Imprecision | Other considerations | |||
| Mean change from baseline in the weekly frequency of cluster headache attacks across weeks 1 through 3 | |||||||||
| 1 | Randomized trial | Not serious | Not serious | Not serious | Serious* | None | Of 106 enrolled patients, 49 were randomly assigned to receive galcanezumab and 57 to receive placebo. The mean (±SD) number of cluster headache attacks per week in the baseline period was 17.8±10.1 in the galcanezumab group and 17.3±10.1 in the placebo group. The mean reduction in the weekly frequency of cluster headache attacks across weeks 1 through 3 was 8.7 attacks in the galcanezumab group, as compared with 5.2 in the placebo group (difference, 3.5 attacks per week; 95% CI, 0.2–6.7; p=0.04). | ⨁⨁⨁◯ | CRITICAL |
| Moderate | |||||||||
| Percentage of patients with a reduction from baseline of at least 50% in the weekly frequency of cluster headache attacks at week 3 | |||||||||
| 1 | Randomized trial | Not serious | Not serious | Not serious | Serious† | None | The percentage of patients who had a reduction of at least 50% in headache frequency at week 3 was 71% in the galcanezumab group and 53% in the placebo group. | ⨁⨁⨁◯ | IMPORTANT |
| Moderate | |||||||||
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| Certainty assessment | No. of patients | Effect | Certainty | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| No. of studies | Study design | Risk of bias | Inconsistency | Indirectness | Imprecision | Other considerations | Triptan | Placebo | Relative (95% CI) | Absolute (95% CI) | |
| Subcutaneous sumatriptan for pain relief at 15 minutes | |||||||||||
| 2 | Randomized trials | Not serious | Not serious | Not serious | Serious |
None | 98/131 (74.8%) | 41/127 (32.3%) | Not estimable | ⨁⨁⨁◯ | |
| Moderate | |||||||||||
| Subcutaneous sumatriptan for pain-free status at 15 minutes | |||||||||||
| 2 | Randomized trials | Not serious | Not serious | Not serious | Serious |
None | 63/131 (48.1%) | 22/127 (17.3%) | Not estimable | ⨁⨁⨁◯ | |
| Moderate | |||||||||||
| Intranasal zolmitriptan for pain relief at 30 minutes | |||||||||||
| 2 | Randomized trials | Not serious | Not serious | Not serious | Serious |
None | 122/229 (53.3%) | 27/111 (24.3%) | Not estimable | ⨁⨁⨁◯ | |
| Moderate | |||||||||||
| Intranasal zolmitriptan for pain-free status at 30 minutes | |||||||||||
| 2 | Randomized trials | Not serious | Not serious | Not serious | Serious |
None | 92/229 (40.2%) | 20/111 (18.0%) | Not estimable | ⨁⨁⨁◯ | |
| Moderate | |||||||||||
| Intranasal sumatriptan pain response at 30minutes | |||||||||||
| 1 | Randomized trial | Not serious | Not serious | Not serious | Serious |
None | Five study centers enrolled 118 patients in whom 154 attacks were treated: 77 with sumatriptan and 77 with placebo. The response rates at 30 minutes were 57% for sumatriptan and 26% for placebo (p=0.002). The pain-free rates at 30 minutes were 47% for sumatriptan and 18% for placebo (p=0.003). | ⨁⨁⨁◯ | |||
| Moderate | |||||||||||
| Oral zolmitriptan for pain relief at 30 minutes | |||||||||||
| 1 | Randomized trial | Not serious | Not serious | Not serious | Serious |
None | Zolmitrptan 10 mg produced significant pain relief at 30 minutes compared with placebo in patients with episodic headache (46.8% versus 28.9%; p=0.02). Zolmitriptan 5 mg in patients with episodic cluster headache was not significantly different from placebo. | ⨁⨁⨁◯ | |||
| Moderate | |||||||||||
| Certainty assessment | Impact | Certainty | Importance | ||||||
|---|---|---|---|---|---|---|---|---|---|
| No. of studies | Study design | Risk of bias | Inconsistency | Indirectness | Imprecision | Other considerations | |||
| Pain-free status at 15 minutes | |||||||||
| 1 | Randomized trial | Not serious | Not serious | Not serious | Serious |
None | Fifty-seven patients with episodic cluster headache and 19 with chronic cluster headache were available for analysis. For the primary end point the difference between oxygen, 78% (95% CI, 71%–85% for 150 attacks) and air, 20% (95% CI, 14%–26%; for 148 attacks) was significant. | ⨁⨁⨁◯ | CRITICAL |
| Moderate | |||||||||
| Pain-free status at 30 minutes | |||||||||
| 1 | Randomized trial | Not serious | Not serious | Not serious | Serious |
None | 72% of oxygen-treated attacks and 24% of placebo-treated attacks were pain-free at 30 minutes. | ⨁⨁⨁◯ | IMPORTANT |
| Moderate | |||||||||
| Certainty assessment | Impact | Certainty | Importance | ||||||
|---|---|---|---|---|---|---|---|---|---|
| No. of studies | Study design | Risk of bias | Inconsistency | Indirectness | Imprecision | Other considerations | |||
| Percentages of patients with two or fewer attacks per day in the 2–4 days after the third injection | |||||||||
| 1 | Randomized trial | Not serious | Not serious | Not serious | Serious |
None | Forty-three patients (15 with chronic and 28 with episodic cluster headache) received cortivazol or placebo. Among the 21 patients who received cortivazol, 20 had a mean of two or fewer daily attacks after injections compared with 12 of 22 controls (odds ratio, 14.5; 95% CI, 1.8–116.9; p=0.012). | ⨁⨁⨁◯ | CRITICAL |
| Moderate | |||||||||
| Total number of attacks between day 1 and day 15 | |||||||||
| 1 | Randomized trial | Not serious | Not serious | Not serious | Serious |
None | Patients who received cortivazol also had fewer attacks (mean, 10.6; 95% CI, 1.4–19.9) in the first 15 days of the study than did controls (mean, 30.3; 95% CI, 21.4–39.3; mean difference, 19.7; 95% CI, 6.8–32.6; p=0.004). | ⨁⨁⨁◯ | IMPORTANT |
| Moderate | |||||||||
| Disappearance of attacks within 72 hours for the 1st week (sustained attack-free 72 hours to 1 week) | |||||||||
| 1 | Randomized trial | Serious |
Not serious | Not serious | Serious |
None | Thirteen patients were allocated to the steroid arm and 10 patients were allocated to the placebo arm. Eleven steroid group patients (85%) became attack-free in the first week after the injection compared to none in the placebo group (p=0.0001). | ⨁⨁◯◯ | CRITICAL |
| Low | |||||||||
| Certainty assessment | Impact | Certainty | Importance | ||||||
|---|---|---|---|---|---|---|---|---|---|
| No. of studies | Study design | Risk of bias | Inconsistency | Indirectness | Imprecision | Other considerations | |||
| Mean number of attacks within the first week of treatment | |||||||||
| 1 | Randomized trial | Not serious | Not serious | Not serious | Serious |
None | The mean number of attacks within the first week of treatment (day 1–7) was 7.1 (SD, 6.5) in the prednisone group compared with 9.5 (SD, 6.0; difference, –2,4; 95% CI, –4.8 to –0.03; p=0.002) in the placebo group. | ⨁⨁⨁◯ | CRITICAL |
| Moderate | |||||||||
| Number of cluster headache attacks after 28 days | |||||||||
| 1 | Randomized trial | Not serious | Not serious | Not serious | Serious |
None | The mean number of cluster headache attacks after 28 days in the prednisone group was still reduced compared with placebo: 15.6 (SD, 15.5) versus 20.2 (SD, 15.0) attacks (difference, –4.7; 95% CI, –11.0 to –1.7, p=0.0356). | ⨁⨁⨁◯ | IMPORTANT |
| Moderate | |||||||||
| 50% reduction in attack frequency at day 7 | |||||||||
| 1 | Randomized trial | Not serious | Not serious | Not serious | Serious |
None | At least a 50% reduction in attack frequency at day 7 was reported by 25 (49%) of 51 patients with prednisone treatment compared with eight (15%) of 55 patients with placebo. | ⨁⨁⨁◯ | IMPORTANT |
| Moderate | |||||||||
| Certainty assessment | Impact | Certainty | Importance | ||||||
|---|---|---|---|---|---|---|---|---|---|
| No. of studies | Study design | Risk of bias | Inconsistency | Indirectness | Imprecision | Other considerations | |||
| Percentage of the patients whose attacks were substantially improved in 1 week | |||||||||
| 1 | Randomized trial | Serious |
Not serious | Not serious | Serious |
None | Thirteen in the lithium group and 14 in the placebo group. | ⨁⨁◯◯ | IMPORTANT |
| Substantial improvement was reached in 62% of the lithium group and 43% of the placebo group. | Low | ||||||||
| Headache index reduction compared to verapamil in preventing chronic cluster headache | |||||||||
| 1 | Randomized trial | Serious |
Not serious | Serious |
Serious |
None | In a randomized crossover trial, both lithium and verapamil reduced headache index in chronic cluster headache, but verapamil had fewer adverse effects and a shorter latency of action. | ⨁◯◯◯ | CRITICAL |
| Very low | |||||||||
| Certainty assessment | Impact | Certainty | Importance | ||||||
|---|---|---|---|---|---|---|---|---|---|
| No. of studies | Study design | Risk of bias | Inconsistency | Indirectness | Imprecision | Other considerations | |||
| Reduced headache attack frequency | |||||||||
| 1 | Randomized trial | Serious |
Not serious | Not serious | Serious |
None | In the second week both the number of attacks (verapamil 0.6±0.88, placebo 1.65±1.01; p<0.001) and the consumption of analgesics (verapamil 0.5±0.87, placebo 1.2±1.03; p<0.004) were lower in the verapamil arm than the placebo arm. | ⨁⨁◯◯ | CRITICAL |
| Low | |||||||||
| Headache index reduction compared to lithium in preventing chronic cluster headache | |||||||||
| 1 | Randomized trial | Serious |
Not serious | Serious |
Serious |
None | In a randomized double-blind crossover trial, both lithium and verapamil reduced chronic cluster headache attacks, but verapamil was associated with fewer adverse effects and a shorter latency of action. | ⨁◯◯◯ | CRITICAL |
| Very low | |||||||||
| Certainty assessment | Impact | Certainty | Importance | ||||||
|---|---|---|---|---|---|---|---|---|---|
| No. of studies | Study design | Risk of bias | Inconsistency | Indirectness | Imprecision | Other considerations | |||
| Mean change from baseline in the weekly frequency of cluster headache attacks across weeks 1 through 3 | |||||||||
| 1 | Randomized trial | Not serious | Not serious | Not serious | Serious |
None | Of 106 enrolled patients, 49 were randomly assigned to receive galcanezumab and 57 to receive placebo. The mean (±SD) number of cluster headache attacks per week in the baseline period was 17.8±10.1 in the galcanezumab group and 17.3±10.1 in the placebo group. The mean reduction in the weekly frequency of cluster headache attacks across weeks 1 through 3 was 8.7 attacks in the galcanezumab group, as compared with 5.2 in the placebo group (difference, 3.5 attacks per week; 95% CI, 0.2–6.7; p=0.04). | ⨁⨁⨁◯ | CRITICAL |
| Moderate | |||||||||
| Percentage of patients with a reduction from baseline of at least 50% in the weekly frequency of cluster headache attacks at week 3 | |||||||||
| 1 | Randomized trial | Not serious | Not serious | Not serious | Serious |
None | The percentage of patients who had a reduction of at least 50% in headache frequency at week 3 was 71% in the galcanezumab group and 53% in the placebo group. | ⨁⨁⨁◯ | IMPORTANT |
| Moderate | |||||||||
GRADE, Grading of Recommendations Assessment; Development and Evaluation; CI, confidence interval. Two randomized controlled trials (RCTs) and small sample size; Study design flawed: allocation and random sequence generation; Single RCT and small sample size; Single RCT and different effect among doses and headache type (episodic vs. chronic).
GRADE, Grading of Recommendations Assessment; CI, confidence interval. Single study.
GRADE, Grading of Recommendations Assessment; CI, confidence interval. Single randomized controlled trial and small sample size; Small sample size.
GRADE, Grading of Recommendations Assessment; SD, standard deviation; CI, confidence interval. Small sample size and single randomized controlled trial.
GRADE, Grading of Recommendations Assessment. Small sample size Headache index reduction compared to verapamil in preventing chronic cluster headache; Not a placebo-controlled trial (comparison with verapamil).
GRADE, Grading of Recommendations Assessment. Small sample size and flawed design; Singe study and small sample size; Not a placebo-controlled trial.
GRADE, Grading of Recommendations Assessment; SD, standard deviation; CI, confidence interval. Single randomized controlled trial (RCT); Single RCT and small sample size.