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Devil's claw for horses: evidence, doping and caution
What is known about devil's claw in horses: a single blood level study, no efficacy study, a clear doping classification by the FEI and FN, and a note of caution for gastric ulcers.
The short answer
For horses, devil's claw is above all a competition issue. The FEI classifies its compound harpagoside as controlled medication, and the FN lists devil's claw as medication prohibited in competition 12. There are no efficacy studies in horses; the only horse study just measures how long the substance stays in the blood 3. If your horse is lame, the cause should be investigated by your vet.
What devil's claw is
Devil's claw is the root of the plant Harpagophytum procumbens. Its key constituent is called harpagoside and is often found in complementary feeds for horses 4.
For humans, the EU medicines agency lists devil's claw only as a traditional herbal medicinal product for mild joint and digestive complaints. This classification is based solely on long-standing use, not on proof of efficacy 5. As a feed, devil's claw may not be advertised as treating disease in any case 6.
What has been studied in horses
There is one study with six horses. They were given a single dose of devil's claw extract via a tube. Harpagoside was detectable in blood plasma for up to nine hours, and no clinically noticeable side effects occurred after this single dose 3.
The study measures how the substance is absorbed and broken down. Whether devil's claw changes lameness or joint problems in horses was not investigated. There are no horse data on long-term use. A review rates the human studies on osteoarthritis as methodologically weak 7.
Devil's claw in competitive sport
Devil's claw is one of the few herbs named explicitly in competition rules.
- FEI: harpagoside has been on the list as controlled medication since 1 January 2016 41.
- FN: Annex II of the ADMR names “Harpagophytum Procumbens (Teufelskralle)” as prohibited medication 2.
- Withdrawal: an FN vet mentions four days in an interview 8. The ADMR database is binding 9.
| Rules | Classification |
|---|---|
| FEI | Controlled medication, since 2016 |
| FN (ADMR) | prohibited medication in competition |
| Withdrawal | 4 days according to FN vet |
Classification in competitive sport; the current version always applies.
Caution with stomach problems
For humans, the EU monograph names an active gastric or duodenal ulcer as a contraindication and gastrointestinal complaints as a possible side effect 5. This has not been investigated in horses.
If your horse has known or suspected stomach problems, you should only give devil's claw after consulting your vet.
Key takeaways
Frequently asked questions
Is devil's claw doping for horses?
In competitive sport, yes. The FEI classifies harpagoside as controlled medication 1, and the FN (German Equestrian Federation) lists devil's claw as medication prohibited in competition 2.
How long before a competition must devil's claw be stopped?
An FN vet mentions a withdrawal period of four days in an interview 8. The ADMR database is binding 9; agree the withdrawal period with your vet.
Does devil's claw help with osteoarthritis?
This has not been investigated in horses. The horse study only measured the blood level after a single dose 3. A review describes the human studies as methodologically weak 7. Osteoarthritis needs veterinary treatment.
Can a horse with a gastric ulcer be given devil's claw?
Clarify this with your vet beforehand. In humans, an active gastric ulcer is considered a contraindication 5. Whether this applies to horses has not been investigated.
Sources & studies
The content is based on the references listed below. It does not replace individual veterinary or feeding advice.
Show list of sources (9)
- FEI (2024): 2025 Equine Prohibited Substances List. Fédération Équestre Internationale, Lausanne, Stand 25.11.2024Version checked: 2025 (the 2026 version could not be accessed on 18 October 2026). Harpagoside is listed as CONTROLLED (analgesic), valerenic acid as CONTROLLED, capsaicin as BANNED. Silibinin/silymarin, Vitex constituents (agnuside, casticin), nettle, rosehip and ascorbic acid are not listed by name. Catch-all clause: substances with a similar chemical structure or similar biological effect are also prohibited. The list is revised annually; the current version always applies
- Deutsche Reiterliche Vereinigung (FN): Anti-Doping- und Medikamentenkontroll-Regeln für den Pferdesport (ADMR) mit Verbotsliste Anhang I–IIIRulebook with its own FN prohibited list (Art. 4.1). Annex II (prohibited medication, banned in competition) explicitly names “Harpagophytum Procumbens (Teufelskralle)” (devil's claw) under the musculoskeletal system and, under “Darüber hinaus sind verboten” (also prohibited), lists in general terms “Phytotherapeutika, wie z.B. Arnika, Ingwer” (phytotherapeutics such as arnica, ginger). Catch-all clause for substances with a similar structure or effect. Responsible persons are personally liable for everything administered to the horse (Art. 2.1.1), including with contaminated feed supplements (commentary on Art. 10.4). The document bears no date
- Axmann S, Hummel K, Nöbauer K, Razzazi-Fazeli E, Zitterl-Eglseer K (2019): Pharmacokinetics of harpagoside in horses after intragastric administration of a Devil's claw (Harpagophytum procumbens) extract. Journal of Veterinary Pharmacology and Therapeutics 42(1):37–446 horses in a crossover, Harpagophytum extract given intragastrically at 5 or 10 mg harpagoside per kg body weight; detectable in plasma for up to 9 hours. Pharmacokinetics only – no efficacy data
- British Showjumping (2015): Revised Equine Prohibited Substances List – Key Changes. News vom 22.12.2015Association announcement: harpagoside (devil's claw, from the root of Harpagophytum procumbens) is added to the FEI list as Controlled Medication from 1 January 2016. Devil's claw is often contained in complementary feeds for horses. No guarantee that complementary feeds are free from prohibited substances
- European Medicines Agency, HMPC (2016): European Union herbal monograph on Harpagophytum procumbens DC. and/or Harpagophytum zeyheri Decne., radix. EMA/HMPC/627057/2015Human medicinal monograph, adopted on 12 July 2016. Traditional use only (based exclusively on long-standing use) for mild joint pain and mild digestive complaints. Contraindication: active gastric or duodenal ulcer. Caution with gallstones. Side effects: gastrointestinal complaints (diarrhoea, nausea, vomiting, abdominal pain), headache, dizziness, hypersensitivity reactions. Not transferable to horses – context from human medicine only
- Verordnung (EG) Nr. 767/2009Placing on the market and use of feed, labelling and claims; definitions of complete feed (Art. 3(2)(i)) and complementary feed (point (j)), content of feed additives (Art. 8), feeding instructions (Annex II No. 4). Link to the current EUR-Lex consolidated version (as of 26 December 2018).
- Brien S, Lewith GT, McGregor G (2006): Devil's Claw (Harpagophytum procumbens) as a treatment for osteoarthritis: a review of efficacy and safety. Journal of Alternative and Complementary Medicine 12(10):981–993Review of 14 human studies; methodological quality is described as weak overall. Not transferable to horses – serves solely as context from another species
- Joschko L (2023): Fairer Sport – Risiko unbewusstes Doping. Pferd und Mensch (FN-Magazin) 04/2023FN (German Equestrian Federation) members' magazine with an interview with Dr Michael Mäule: devil's claw is “fundamentally not ADMR-compliant” and has “a withdrawal period of four days”. Herbs acting on digestion or the airways (examples fennel, ribwort plantain, chamomile) are also often ADMR-relevant. In feeds, a limit of 0.5% per herb often applies. Secondary source (interview); the ADMR database is authoritative
- FN – Anti-Doping und Medikation (ADMR-Suchmaschine)Official database of the FN (German Equestrian Federation) on substances and withdrawal periods in competitive sport