Why Herbal Supplements for Horses Are So Popular
Walk into any tack shop or scroll through an equine supplies website and you'll find shelves packed with herbal supplements for horses. From calming blends to joint-support formulas, the market is booming — and it's easy to see why. Many horse owners prefer a natural approach to health, and herbs have been used in equine care for centuries.
But popularity doesn't always equal effectiveness. Some herbal products are genuinely beneficial and supported by research, while others are little more than expensive sprinkles on your horse's feed. Worse still, a few can actually be harmful if used incorrectly.
This guide will walk you through everything you need to know about herbal supplements for horses — which ones have real evidence behind them, how to use them safely, and what to watch out for before you spend your money.
What Counts as an Herbal Supplement?
An herbal supplement is any product derived from plants — leaves, roots, bark, flowers, or seeds — that is fed to a horse with the intention of supporting health, behaviour, or performance. These are distinct from pharmaceutical drugs, although the line can sometimes blur. Many modern medicines were originally derived from plants (aspirin from willow bark, for example).
Herbal supplements for horses typically come in several forms:
- Dried herbs — loose or chopped plant material added to feed
- Powders — ground herbs, sometimes blended together
- Liquid extracts or tinctures — concentrated preparations using alcohol or glycerine
- Pellets or granules — herbs processed into easy-to-feed formats
Some products contain a single herb, while others combine several ingredients into a proprietary blend.
Popular Herbal Supplements and What the Evidence Says
Let's look at some of the most commonly used herbs in equine nutrition and examine what science actually tells us about them.
Valerian
Valerian root is one of the most well-known calming herbs. It has a long history of use in both human and equine herbal medicine. Some studies suggest that valerian can have mild sedative effects by influencing GABA receptors in the brain.
What owners should know: Valerian is a banned substance under FEI rules and many national competition bodies. If your horse competes, using valerian could result in a positive drug test and disqualification. Always check the rules of your discipline before feeding any calming supplement.
Devil's Claw
Devil's claw (Harpagophytum procumbens) is widely used for its anti-inflammatory properties, particularly for joint stiffness and musculoskeletal discomfort. There is reasonable evidence from human studies that devil's claw can reduce inflammation, and anecdotal reports from horse owners are generally positive.
What owners should know: Like valerian, devil's claw is a prohibited substance in competition. It should also be used with caution in horses with gastric issues, as it may increase stomach acid production. It is not a substitute for proper veterinary diagnosis and treatment of lameness.
Chamomile
Chamomile is a gentle herb used for calming and digestive support. It contains compounds like bisabolol and chamazulene that have mild anti-inflammatory and antispasmodic properties.
What owners should know: Chamomile is generally considered safe and is not currently a banned substance in most competition settings. However, its calming effects in horses tend to be very mild, so don't expect dramatic changes in a highly anxious horse.
Turmeric (Curcumin)
Turmeric has exploded in popularity in the equine world, largely driven by its use in human health. The active compound, curcumin, does have demonstrated anti-inflammatory and antioxidant properties in laboratory settings.
What owners should know: The challenge with turmeric is bioavailability. Curcumin is poorly absorbed in the gut. Many owners feed turmeric with black pepper (piperine) and oil to improve absorption, but even then, it's unclear how much active curcumin actually reaches the tissues where it's needed. Research specifically in horses is still limited.
Milk Thistle
Milk thistle (Silybum marianum) is the go-to herb for liver support. Its active compound, silymarin, has been studied quite extensively in other species and has shown genuine hepatoprotective effects.
What owners should know: If your horse has been exposed to toxic plants, certain medications, or other liver stressors, milk thistle may be a useful supportive supplement. However, liver problems in horses should always be diagnosed and monitored by a vet — don't rely on milk thistle alone.
Garlic
Garlic is one of the most commonly fed herbs to horses, usually as a fly deterrent. Some owners also feed it for respiratory support or general immune health.
What owners should know: This is one where caution is genuinely warranted. Research has shown that feeding garlic to horses in significant quantities can cause Heinz body anaemia — a condition where red blood cells are damaged. A study by Pearson et al. (2005) found that horses fed garlic at commonly recommended doses showed measurable changes in red blood cell parameters. If you choose to feed garlic, use very conservative amounts and take regular breaks.
Echinacea
Echinacea is often promoted for immune support, particularly during times of stress or when a horse is fighting off an infection. Evidence from human studies is mixed, and equine-specific research is sparse.
What owners should know: Echinacea is generally considered safe for short-term use, but long-term continuous feeding is not recommended. It may also interfere with immunosuppressive medications, so check with your vet if your horse is on any drug therapy.
Hawthorn
Hawthorn berries and leaves are used to support cardiovascular health and circulation. There is some evidence in humans to support this, but research in horses is very limited.
What owners should know: Hawthorn may interact with cardiac medications. If your horse has a diagnosed heart condition, consult your vet before adding hawthorn to the diet.
The Regulatory Landscape: What You're Actually Buying
One of the biggest issues with herbal supplements for horses is regulation — or rather, the lack of it. In most countries, herbal supplements are classified as feed products, not medicines. This means:
- They don't need to prove they work before being sold
- Quality control varies enormously between manufacturers
- Labels can be vague about exact quantities of active ingredients
- There's no requirement for clinical trials or standardised dosing
This doesn't mean all herbal products are bad. Many reputable companies invest in quality sourcing, testing, and transparent labelling. But it does mean you need to be a savvy consumer.
How to Choose a Quality Herbal Product
- Look for products that clearly state the species of plant used and the part of the plant (root, leaf, etc.)
- Check whether the manufacturer provides a guaranteed analysis or specifies the concentration of active compounds
- Choose companies that can provide batch testing or certificates of analysis
- Be wary of products with vague proprietary blends that don't disclose individual ingredient amounts
- Look for brands with a good reputation in the equine community and endorsements from qualified nutritionists or vets
Herbal Supplements and Competition Rules
This cannot be overstated: many herbal ingredients are banned in competition. The FEI's Equine Prohibited Substances List includes numerous plant-derived compounds. National governing bodies in the UK, US, Australia, and elsewhere have similar lists.
Commonly banned herbal substances include:
- Valerian
- Devil's claw
- Hops
- Passionflower
- Comfrey (also toxic to the liver)
- Kava kava
Even products marketed as "competition safe" should be treated with caution. Contamination or undeclared ingredients in herbal products have caused positive drug tests in the past. If you compete at any level, the safest approach is to withdraw herbal supplements well before competition or avoid them altogether during the competitive season.
Can Herbs Replace Veterinary Care?
The short answer is no. Herbal supplements can play a supporting role in your horse's health management, but they should never replace proper veterinary diagnosis and treatment.
If your horse is lame, losing weight, showing signs of pain, or behaving abnormally, the first call should be to your vet — not to a supplement catalogue. Using herbs to mask symptoms can delay diagnosis and allow problems to get worse.
That said, herbs can complement conventional care when used thoughtfully. For example, milk thistle alongside veterinary-prescribed treatment for liver issues, or chamomile to support a horse with mild digestive sensitivity. Always tell your vet what supplements you're feeding, as some herbs can interact with medications.
How Herbal Supplements Fit Into the Bigger Nutritional Picture
Before adding any supplement — herbal or otherwise — it's essential to make sure the basics of your horse's diet are right. No herb can compensate for a diet that's deficient in essential vitamins, minerals, or quality forage.
The most important thing you can do before reaching for a herbal product is to analyse your horse's diet to identify any genuine nutritional gaps. Once the foundation is solid, you can make informed decisions about whether a herbal supplement might offer additional benefits for your horse's specific needs.
Many horses are over-supplemented — their owners are spending money on multiple products that overlap or conflict, while the basic diet remains unbalanced. Getting the fundamentals right first is always more impactful than layering on extra supplements.
Practical Tips for Feeding Herbal Supplements Safely
If you've decided that a herbal supplement is appropriate for your horse, here are some practical guidelines:
Start Low and Slow
Introduce any new supplement gradually. Start with half the recommended dose and increase over a week or two. Monitor your horse for any changes — positive or negative.
Feed One New Product at a Time
If you introduce multiple supplements at once, you won't know which one is responsible for any changes you observe. Add one product, give it at least 3–4 weeks, and assess before adding another.
Take Breaks
Many herbalists recommend cycling herbal supplements — feeding for a period and then taking a break. This can help prevent the body from adapting and may reduce the risk of side effects from long-term use. A common approach is 5–6 weeks on, 1–2 weeks off.
Keep Records
Note down what you're feeding, the dose, and any observations about your horse's behaviour, movement, coat condition, or appetite. This helps you evaluate whether the supplement is actually making a difference or whether it's just a placebo effect on the owner.
Watch for Adverse Reactions
Signs that a herbal supplement isn't agreeing with your horse can include:
- Loose droppings or changes in manure consistency
- Reduced appetite
- Skin reactions or itching
- Increased irritability or unusual behaviour
- Lethargy
If you notice any of these, stop feeding the supplement and consult your vet.
The Bottom Line on Herbal Supplements for Horses
Herbal supplements can be a valuable part of your horse's health toolkit — but only when used wisely. Here's a quick summary:
- Some herbs have genuine evidence supporting their use (devil's claw, milk thistle, chamomile)
- Others are popular but under-researched in horses (turmeric, echinacea)
- A few carry real risks if misused (garlic, comfrey, valerian in competition horses)
- Quality and regulation vary widely, so choose reputable brands
- Always check competition rules before feeding herbal products
- Herbs are not a replacement for veterinary care or a balanced diet
- Get the dietary basics right first — then consider targeted herbal support
The best approach is an informed one. Do your research, consult your vet or a qualified equine nutritionist, and don't fall for marketing hype. Your horse deserves evidence-based care, whether it comes from a pharmacy or a plant.