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Cramp Bark (Viburnum opulus)
Relaxes smooth muscle tissue through scopoletin compounds, primarily used for menstrual cramps and muscle spasms.
What the evidence says
Most Cramp Bark studies are mechanism or observational rather than RCTs that measure a clinical effect — keep findings provisional.
Most evidence is from medium-quality randomised trials published 2014–2025 with a typical study size of 86 participants.
Based on 7 studies · 1 RCT · 86 total participants
Confidence
LowWhat the studies found
By outcome
Cramp Bark has an evidence score of 6/10 — moderate evidence based on 7 indexed studies. Relaxes smooth muscle tissue through scopoletin compounds, primarily used for menstrual cramps and muscle spasms.
The commonly studied dose of Cramp Bark is 500-1000mg extract or 2-4g dried bark. Research points to an estimated optimal dose around 1000mg, with a minimum effective dose near 500mg. Individual response varies — start low and adjust.
Timing is flexible for Cramp Bark — consistent daily use matters more than the time of day. Cramp bark (Viburnum opulus) contains viopudial, scopoletin, and other antispasmodic compounds that relax smooth muscle.
Last reviewed May 2026 · evidence from 10 studies · how we score
This information is for educational purposes only. It is not a substitute for professional medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any supplement or medication.
Cramp Bark, as its name suggests, has been used traditionally to relieve muscle cramps and spasms, particularly menstrual cramps. It's a close relative of Black Haw and shares similar properties. The bark contains scopoletin and other compounds that appear to relax smooth muscle tissue.
Relaxes smooth muscle tissue
May specifically relax uterine muscle
How Cramp Bark works — from molecular targets to health outcomes. Click an edge to see supporting research.This visualization is in beta — pathways are being refined and expanded.
500-1000mg extract or 2-4g dried bark
Loading: Not required; use as needed
Take with food
| Form | Type |
|---|---|
| 💊Tincture or capsules | Recommended |
| 🍵Dried bark tea | Alternative |
| 💊Extract | Alternative |
Tincture works fastest. Tea requires longer steeping (15-20 min).
Minimum: 1 days
Optimal: 4 days
Cycling: Use as needed during menstruation; not for continuous daily use
Note: Most effective when taken at the first sign of cramps. Can be used preventively starting a day before expected menstruation.
Based on single RCT (n=86) showing reduced analgesic requirement vs tamsulosin for ureteral stones. Limited to short-term use data. No menstrual cramp studies despite claims.
Reduced menstrual cramp intensity
General smooth muscle relaxation
Consult healthcare provider; traditionally used for threatened miscarriage
Contains salicin; may have mild antiplatelet effects — may affect platelet aggregation or vitamin K-dependent clotting factors, altering anticoagulant efficacy
Tip: Take with food
Cramp Bark is generally well-tolerated and considered safe for most healthy adults at recommended doses. The most commonly reported side effects are GI upset. Use caution if any of these apply to you: Aspirin allergy (contains salicin).
Wild Yam
Probably helpsContains diosgenin, a phytosteroid that may ease menopausal symptoms and menstrual discomfort through non-hormonal pathways.
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