In the stable, it usually starts innocently enough. A horse is given a new devil's claw supplement because someone wants to help it move more comfortably, and a few days later its droppings become looser, its appetite falls or it becomes reluctant to eat its feed. That is when the most important question arises: is this simply a brief adjustment, or are these already devil's claw side effects that require action?
In practice, I usually see subtle digestive signs rather than anything dramatic. This fits with descriptions in Polish sources, which most often list diarrhoea, nausea, vomiting, abdominal pain and loss of appetite, as well as headaches, dizziness, ringing in the ears and changes in blood pressure. Topical products may cause allergic skin reactions. Source from Polish pharmacy and popular science publications
Practical rule: if a horse starts eating less well, has looser droppings or seems clearly out of sorts after starting a supplement, I first stop the product and observe, rather than immediately adding further treatments.
When devil's claw starts causing problems in horses
In the stable, the first signs are usually very subtle. The horse approaches its manger but leaves some feed, eats more slowly than usual or loses interest in feeding, despite previously eating without hesitation. Owners often put this down to the weather, training or a change of hay, which is precisely why a slight drop in appetite after introducing devil's claw deserves to be treated as a warning sign.
The earliest change is seen at feeding time. The horse may pick through its feed, spend less time at the manger than usual or walk away after a few mouthfuls and only return much later. Sometimes the first clue is a subtle change in eating speed, noticeably less enthusiasm for a meal or the horse starting to leave leftovers when it previously left none.
These are the signs I most often observe in practice before anything more obvious appears. If a horse becomes less willing to eat after a supplement is introduced, starts rummaging through its feed or backs away from the manger, I first stop the product and see whether its behaviour returns to normal. Polish safety sources stress that adverse effects are usually rare and mild, and are more likely to appear with excessive doses or incorrect use. Polish review of the safety and uses of devil's claw
What you notice first as an owner
The first symptom does not have to be an obvious illness. Often it is simply a horse that starts eating more cautiously, is less interested in hard feed or seems less settled at feeding time after a few days of supplementation. There may also be a slight change in its behaviour during its daily routine: the horse stands more apart, is less eager to eat and seems as though something is putting it off its feed.
At this point, observation matters more than panic. If the symptom is mild, brief and disappears after the supplement is withdrawn, this usually suggests intolerance rather than a severe reaction. However, if the horse's eating declines noticeably, it becomes lethargic, refuses feed repeatedly or its behaviour at the manger changes from one day to the next, you need to contact your vet.
A horse cannot tell you directly that a supplement does not agree with it. It shows you at the manger, through its eating speed and whether it still wants to approach its feed.
How devil's claw works and why it can irritate the digestive tract
Devil's claw, or Harpagophytum procumbens, contains iridoid compounds responsible for its anti-inflammatory and pain-relieving effects. In practice, this means the plant is intended to help where the musculoskeletal system responds with pain and stiffness, but the same action can affect the stomach and intestines in some horses. This is precisely why we talk about balancing effects with tolerance.
Where irritation comes from
Polish literature repeatedly warns that devil's claw can irritate the lining of the digestive tract, especially in animals with existing gastrointestinal problems. This matters because a horse does not need to have severe gastric ulcers to tolerate a supplement poorly. Its digestive system may simply already be under strain, for example from a dietary change, stress in the stable or more intensive work.
You should also understand that herbal supplements do not act in isolation. If a horse is also receiving anti-inflammatory products or has a sensitive digestive tract, the risk of increased discomfort is simply greater. With devil's claw, the question is therefore not merely how natural the product is, but how its action fits that individual animal.
Which horses are more likely to react badly
I am most vigilant with horses that have previously had loose droppings, episodes of colic after feed changes or generally sensitive digestion. Such a reaction is not proof that the supplement is toxic. Rather, it shows that the horse may need a different form of support or lower exposure to the same ingredient.
In everyday stable management, spotting the sign early is what matters most. When you respond straight away, you can usually stop the problem at the stage of mild intolerance rather than allowing fully developed digestive problems to emerge.
The most common side effects of devil's claw in horses
In the stable, dramatic reactions are less common than subtle signs that are easily dismissed as an off day. With devil's claw, these are precisely the signs that matter most. The most common problem is digestive tract irritation, meaning looser droppings, reduced appetite, reluctance to eat feed or brief abdominal discomfort. In some horses, the problem is limited to mild, temporary intolerance and resolves after withdrawal or a reduction in dosage.
With topical products, the picture can be different. Instead of intestinal symptoms, you may see reddened skin, itching, a local burning sensation or marked sensitivity at the application site. This is not something to wait out. If the skin reacts this way, the product usually needs to be stopped and the horse assessed to see whether further examination is required.
How to distinguish adjustment from an adverse reaction
In practice, timing and severity matter. A slight change in droppings after starting a supplement, without reduced energy or pain, may simply indicate that the digestive tract needs to adjust. The situation is different when the horse loses its appetite, becomes noticeably dull, refuses food or begins showing pain. I treat that picture as a real warning sign rather than ordinary adjustment to a herb.
With devil's claw, assessing just one symptom in isolation makes little sense. A single loose dropping need not mean there is a problem, but loose droppings combined with reluctance to eat and reduced comfort are a different matter. In a horse with previously sensitive digestion, you should not become less cautious.
When a reaction means the product must be stopped
I stop the supplement if symptoms are clear, persist beyond a passing episode or worsen after subsequent doses. This applies especially to horses with a history of gastrointestinal problems, as a seemingly minor reaction can develop into a bigger problem more quickly. With skin symptoms, the decision is usually simpler: local irritation after a topical product should not persist.
You should also remember the context of the whole treatment plan. If the horse is receiving other anti-inflammatory products at the same time or its diet has changed, it is easy to mistake the cause of the symptoms. That is why I consider the whole picture, from feed to training workload, as well as devil's claw itself.
What you see first as an owner
The earliest sign is usually reduced enthusiasm for eating. A change in the consistency of droppings or nervousness during tacking up and handling then follows, because the horse simply feels worse. Skin symptoms are less often the first sign, but if the product was applied topically, the skin may be the first place to react.
This is a practical distinction worth remembering. A brief, mild change after starting supplementation can be monitored, but pain, a marked drop in appetite, persistent diarrhoea or a skin reaction following contact with the product require you to stop using it and contact your vet.
Risk in numbers: what research says about devil's claw safety
It is easy to exaggerate when discussing devil's claw. Some see it as an almost risk-free herb, while others describe it as a supplement to fear. The data are more measured: a safety analysis covering 28 clinical studies found no greater incidence of adverse effects than in the placebo group, while side effects were reported in around 3% of people and mainly involved the digestive system. Safety analysis of devil's claw across 28 studies
What this means in practice
This is not a highly toxic supplement. At standard doses, the risk is usually low, and problems are more likely when a product is introduced too aggressively or without considering stomach sensitivity. That is exactly why I place such emphasis on observation during the first few days after starting the product.
As a horse owner, the scale matters too. 3% is not a figure that should put you off devil's claw itself, but it is enough to show that it should not be treated as an entirely neutral dietary addition. If your horse responds well, that is fine. If not, there is no point waiting out clear intestinal symptoms.
Why research matters more than rumours
The internet favours extremes. Research shows something more useful: the problem is not widespread, but it does exist and is usually mild and digestive in nature. This gives you a real point of reference instead of a general fear of every herb.
It is also worth noting that research data and Polish warnings do not contradict each other. You can say both that devil's claw is generally well tolerated and that it can irritate the digestive tract in some horses. This is an honest description of risk rather than a conflict.
Contraindications: when it is better to avoid devil's claw in horses
I would be most cautious with horses with gastric and duodenal ulcers. Polish sources repeatedly state that devil's claw can irritate the digestive tract lining, so an existing problem makes it easy to worsen the animal's comfort. The same applies to horses with chronic digestive complaints, where every additional trigger may be keenly felt.
When medication is involved
Combining devil's claw with anticoagulants and NSAIDs requires particular caution. Polish literature highlights the possibility of worsening irritation or increasing bleeding risk. This is the point where a supplement stops being an ordinary addition and becomes part of a treatment plan requiring veterinary assessment.
Practical stable rule: if your horse is receiving pain medication or something for its blood, you should not add devil's claw on your own initiative.
When caution is needed rather than permission to experiment
Pregnancy, liver disease and longstanding digestive problems are situations where I would not base a decision solely on the supplement label. In these cases, individual risk assessment matters because the body's response may be less predictable. The same applies to horses that have previously developed diarrhoea or reduced appetite after herbal products.
In practice, the useful question is not whether devil's claw is natural, but whether this particular horse is in a position to tolerate it well. With gastric ulcers, the answer is usually no. With stable digestion, the answer may be yes, but with observation and a sensible dose.
Symptoms that mean you must stop
If clear abdominal pain, persistent diarrhoea, reduced appetite or obvious lethargy appear after starting the supplement, the product should be withdrawn. With topical products, any pronounced skin reaction is also a signal to stop use. This is no time to test your horse's patience.
Drug interactions and practical dosage advice
Devil's claw can be an ingredient in pain-relieving and anti-inflammatory products, but that very fact makes it easy to combine it too casually with other treatments. If your horse receives NSAIDs, joint support products or medicines that affect clotting, or is prone to stomach irritation, you need to consider the whole picture rather than a single product. These are precisely the situations where advice from your vet or a carefully chosen product from one source can help, for example from the VETfactory range when you need a horse supplement with a clearly described purpose.
How to approach the first few days
I do not start at full intensity if the horse has never received this ingredient before. The most sensible approach is to introduce the supplement gradually and then observe appetite, droppings, behaviour during work and general comfort during the first few days after the change. If everything is stable, you can continue. If diarrhoea or discomfort appears, the dose must be reduced or the product stopped.
You should also make sure you do not change too many parts of the diet at once. Otherwise, it is difficult to establish what actually caused harm. A new supplement, new hay and a new medicine in the same week are a recipe for diagnostic confusion.
What to watch and when to act
- Appetite: if the horse starts leaving feed or picks out only part of its meal, I treat this as an early sign of intolerance.
- Droppings: softer droppings, diarrhoea or a change in bowel habits require supplementation to be stopped.
- Behaviour: reluctance to work, lethargy or obvious discomfort matter more than whether the supplement was supposed to help the joints.
- Skin with topical products: itching, redness and irritation mean the product does not agree with your horse.
When to stop the supplement immediately
If symptoms involve several systems, meaning the horse eats less well, has problems with its droppings and looks unwell at the same time, I would not wait for its body to get going. This is no longer ordinary adjustment. With this combination of signs, you need to contact your vet.
Keeping simple observations after every new supplement is also good practice. You do not need spreadsheets or apps. Simply remember what the appetite was like, what the droppings were like and whether the horse behaved normally. This routine saves a great deal of guesswork.
If you are looking for horse supplements and feeds that can be chosen calmly and thoughtfully for a particular problem, visit VETfactory. The range includes products for competition, leisure and senior horses, and when choosing a devil's claw product or an alternative for joint support, you can easily compare ingredients and intended uses. If you want to discuss your horse's tolerance of a supplement, it is worth starting with an option suited to its digestive tract and current treatment.
