Devils Claw Side Effects and Safety UK — Everything You Need to Know

Written by Chris Jones, Social Media Manager at Nutrivity with 7+ years in the supplement industry.

Devils claw has a well-documented and generally favourable safety profile in clinical research, with most trials reporting low adverse event rates and good tolerability. However, it has specific contraindications and drug interactions that are clinically significant and should be understood before starting supplementation. This guide covers the known side effects, who should not take devils claw, and the drug interactions that matter most.

For a full overview of what devils claw is, see our guide to what is devils claw. For dosage guidance, see our devils claw dosage UK guide. For the full interactions guide, see our article on devils claw and medications. For full product information, visit our Devils Claw 2200mg Vegan Capsules product page.

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Common Side Effects

In clinical trials, the most commonly reported side effects of devils claw are gastrointestinal — nausea, stomach upset, diarrhoea, and abdominal discomfort. These effects are related to the bitter iridoid compounds in devils claw root, which stimulate gastric acid secretion. They are generally mild, dose-dependent, and substantially reduced by taking devils claw with food rather than on an empty stomach.

Headache and dizziness are occasionally reported but are uncommon and not consistently demonstrated in controlled trials. Skin reactions (rash, urticaria) are rare but have been reported. Allergic reactions to devils claw are rare but possible in people with known sensitivities to plants in the Pedaliaceae family.

In the comparative trials — including the back pain trials against COX-2 inhibitors and the OA trial against diacerhein — devils claw consistently showed fewer gastrointestinal adverse events than the pharmaceutical comparators. This is one of its key safety advantages for long-term use.

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Who Should Not Take Devils Claw

People with stomach or duodenal ulcers. The bitter compounds in devils claw stimulate gastric acid production. In people with active ulcers or a history of ulcers, this may exacerbate the condition. Devils claw is contraindicated in active peptic ulcer disease.

Pregnant women. Devils claw has demonstrated oxytocic activity (uterine stimulation) in research models. It should not be taken during pregnancy. This contraindication is clearly stated in EMA and Commission E guidance.

People with gallstones. Devils claw increases bile production. In people with gallstones, increased bile flow may trigger biliary colic. It is contraindicated in people with known gallstones.

People with certain heart conditions. Some research suggests devils claw may affect heart rate and rhythm. People with cardiac arrhythmias should consult a cardiologist before taking devils claw.

People with hormone-sensitive cancers. Some research suggests minor oestrogenic activity. People with oestrogen-receptor positive cancers should discuss with their oncologist before use.

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Drug Interactions

Warfarin and anticoagulants. The most significant interaction. Devils claw may potentiate the anticoagulant effect of warfarin, increasing bleeding risk. Case reports of elevated INR in warfarin patients taking devils claw have been published. If you take warfarin or any other anticoagulant, do not take devils claw without GP guidance and INR monitoring.

NSAIDs. Concurrent use of devils claw and NSAIDs is generally safe but redundant — both target inflammatory pathways and taking both together is unlikely to provide additional benefit over either alone at adequate doses. If you are transitioning from NSAID use to devils claw, discuss with your GP.

Antidiabetic medications. Some research suggests devils claw may lower blood glucose. People taking insulin or oral hypoglycaemic drugs should monitor blood glucose carefully when starting devils claw and inform their GP.

Antacids. Antacids may reduce the absorption of devils claw’s active compounds. Take devils claw and antacids at separate times — at least two hours apart — if you use both.

Antiarrhythmic medications. Given the potential cardiac effects noted above, people taking antiarrhythmic drugs should consult their cardiologist before starting devils claw.

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Is Devils Claw Safe for Long-Term Use?

Clinical research has used devils claw for up to four months continuously without emerging safety concerns. Traditional use in southern African and European herbal medicine has a long history at recommended doses. No cumulative toxicity has been identified. For adults without the contraindications listed above and not taking the medications noted, long-term daily supplementation at recommended doses is appropriate. Annual GP review is sensible for any long-term supplement use alongside any prescription medication.

Summary — Devils Claw Safety

Devils claw has a good safety profile in clinical research at recommended doses, with gastrointestinal effects being the most common adverse events and these substantially reduced by taking it with food. The key contraindications — peptic ulcer disease, pregnancy, gallstones — are specific and manageable. The most significant drug interaction is with warfarin, requiring GP awareness and INR monitoring. For adults without these contraindications and not on interacting medications, daily devils claw supplementation is safe and well-tolerated.

For full product information and to purchase, visit Nutrivity’s Devils Claw 2200mg Vegan Capsules product page.

Frequently Asked Questions