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The short version: GastroGard and UlcerGard are the same drug, omeprazole paste, in the same 2.28 g tube. GastroGard is prescription-only and labeled to treat ulcers; UlcerGard is sold over the counter and labeled only to prevent them, at a quarter of the treatment dose. What most owners are never told: omeprazole heals ulcers in the upper, squamous part of the stomach about three times out of four, but ulcers in the lower, glandular part only about one time in four. Those glandular ulcers are the kind bute causes. Which kind your horse has can only be seen with a scope.
GastroGard vs UlcerGard: What Is the Difference?
Same active ingredient, same tube. Different label, different dose, different rules.
Both products are made by Boehringer Ingelheim and contain omeprazole, a proton pump inhibitor that shuts down acid production in the stomach. Each tube holds 2.28 g of omeprazole. The difference is what the FDA approved each one to do.
| GastroGard | UlcerGard | |
|---|---|---|
| Labeled use | Treat gastric ulcers and prevent them from coming back | Prevent gastric ulcers only |
| How to buy | Prescription from your vet | Over the counter, no prescription |
| Dose | 4 mg/kg once daily for 4 weeks to treat, then 2 mg/kg for at least 4 more weeks to prevent recurrence | About 1 mg/kg once daily: one quarter-tube dose for horses 600 to 1,200 lb, two doses over 1,200 lb |
| Labeled duration | Treatment 28 days; safety beyond 91 days not determined | Up to 28 days during stressful periods |
| FDA approval | NADA 141-123 | NADA 141-227 |
| Generic | Gastrobim (Bimeda), approved April 2026, prescription | None approved |
Can you use UlcerGard to treat ulcers? Technically you can give enough UlcerGard paste to reach the 4 mg/kg treatment dose, since the drug is identical. But that is using an over-the-counter product off-label to treat a disease nobody has diagnosed, and you would still not know which type of ulcer you are dealing with. That is the bigger problem, and it is the subject of the next section.
Does Omeprazole Work? It Depends Which Ulcer
The single most important fact about ulcer drugs, and the one most product pages leave out.
Since 2015, equine vets have split "equine gastric ulcer syndrome" into two different diseases, because they behave differently and respond differently to treatment. The European College of Equine Internal Medicine consensus statement put it this way:
- Equine squamous gastric disease (ESGD) affects the upper, non-glandular part of the stomach, which has no protection against acid. It is common: roughly 37% of untrained racehorses rising to 80 to 100% once they are in training, 17 to 58% of sport horses and 37 to 59% of pleasure horses. It is mostly a disease of acid exposure, so shutting down acid works well.
- Equine glandular gastric disease (EGGD) affects the lower, glandular part, which normally protects itself with mucus, bicarbonate and prostaglandins. When those defenses break down, ulcers form. Acid is only part of the story, so acid suppression alone works far less well. NSAIDs such as bute damage exactly those prostaglandin defenses.
The numbers are stark. At 4 mg/kg, omeprazole heals squamous ulcers in roughly 70 to 78% of horses within four weeks. For glandular ulcers, the consensus statement puts healing at only about 25% at 28 to 35 days. In a 2019 randomized trial, horses with glandular disease given omeprazole plus sucralfate healed 20% of the time, against 72% on misoprostol. A 2022 study found oral omeprazole healed 42% of glandular cases, against 80% on a long-acting injectable omeprazole. And in a 2023 review of real-world cases at a UK university hospital, only 29% of glandular cases healed overall, with no treatment clearly beating the others.
What that means for you: if your horse has squamous ulcers, a GastroGard course is very likely to work. If your horse has glandular ulcers, especially a horse that has been on bute, a standard 28-day tube course may leave them unhealed, and you would not know without a follow-up scope. This is the strongest argument for scoping before you spend a month's worth of tubes, and again at the end.
Healing matters beyond comfort. In a 2025 Italian study of 17 trained showjumpers, speed and stride length both increased once their ulcers had healed, measured with a fitness tracker during ridden work.
About those GastroGard label figures you may have read (92% healed or improved, 99% in field trials): they are real, but they come from studies done before vets separated the two diseases, in horses where squamous ulcers dominate. They do not tell you how glandular ulcers respond.
How Often to Give UlcerGard or GastroGard, and How Long
Once a day, every day, for as long as the label or your vet says, then taper rather than stop.
- Treatment (GastroGard): 4 mg/kg once daily for 28 days. One tube covers a 1,250 lb horse at this dose, so a 1,000 lb horse needs about 0.8 of a tube a day, or 22 to 23 tubes for the course.
- Preventing recurrence (GastroGard): 2 mg/kg once daily for at least another 28 days, about 11 to 12 tubes.
- Prevention (UlcerGard): one quarter-tube dose daily for horses 600 to 1,200 lb, starting before and continuing through a stressful period such as hauling, showing or a change in training, for up to 28 days. That is 7 tubes a month. In the label study, 82% of horses on UlcerGard stayed ulcer-free under stress, against 14% given a sham dose.
How long should a horse be on GastroGard? The label calls for 28 days of treatment, followed by at least 28 days at the lower dose. Safety beyond 91 days has not been determined, although the label's safety studies were reassuring: horses given five times the dose for 90 days, and ten times the dose for 21 days, showed no drug-related effects. Your vet decides the length, ideally guided by a scope at the end of treatment rather than the calendar.
How long does it take to work? Omeprazole begins suppressing acid within the first day or two, and many owners see appetite and attitude improve within one to two weeks. Healing takes longer: four weeks is the standard checkpoint for squamous ulcers, and the consensus statement recommends at least eight weeks for glandular disease.
Do not stop cold. Ulcers come back quickly once acid returns. In a 2023 randomized trial in Thoroughbred racehorses, squamous disease was back to its starting prevalence after omeprazole was stopped for just two clear days before racing. Ask your vet how to step the dose down at the end of a course and what to do during the highest-risk periods.
Morning, before feed?
The traditional advice is to give omeprazole in the morning, before the first grain meal. Studies of whether feeding reduces absorption in horses have produced mixed results, so the practical rule is consistency: same time, same routine, every day. Put the paste on the back of the tongue, keep the head raised for a few seconds and check it was swallowed.
Is Compounded Omeprazole as Good?
The evidence says probably not, and it is the main thing owners try to save money on.
In a study of 798 horses in race training, scoped by a vet who did not know what each horse was getting, only proprietary omeprazole was linked to lower odds of moderate or severe ulcers. Horses on compounded omeprazole did no better than horses on no treatment at all. Separate studies found a compounded omeprazole suspension failed to heal ulcers in 30 days while the paste reached higher blood levels, and that only GastroGard and one of three compounded preparations raised stomach pH.
Compounded products are not FDA-approved, are not checked for strength or stability, and vary between pharmacies and batches. If cost is the issue, ask your vet about the generic, Gastrobim, which the FDA approved in April 2026 as bioequivalent to GastroGard.
Side Effects and Long-Term Use
Omeprazole is very safe in the short term. Long-term, a few things are worth knowing.
| Concern | What the evidence shows | What to do |
|---|---|---|
| Short-term safety | No drug-related effects at 5 times the dose for 90 days or 10 times the dose for 21 days in the label studies. Stallions given 3 times the dose for 70 days showed no effect on breeding soundness. | Give the prescribed dose; there is no benefit in giving more. |
| Calcium absorption | In a Kentucky Equine Research study, omeprazole cut calcium digestibility from 52.0% to 41.4% on a limestone diet, and blood gastrin doubled. | Ask about diet and calcium for horses on long-term omeprazole, particularly young horses in training. |
| Gut bacteria | Two controlled studies found only minimal changes in the fecal microbiome during omeprazole treatment. | Reassuring, but another reason not to use it indefinitely without a reason. |
| Rebound acid | Ulcers can return within days of stopping. | Taper rather than stop abruptly, with your vet's plan. |
| Combined with bute | In a randomized trial, horses given bute plus omeprazole had more intestinal complications than horses on bute alone. | Do not assume omeprazole makes bute safe. See our bute guide. |
What Else Treats Ulcers? Sucralfate, Misoprostol and Injectables
Especially for glandular ulcers, omeprazole is often only part of the plan.
| Drug | How it works | Best evidence for |
|---|---|---|
| Omeprazole (GastroGard, UlcerGard, Gastrobim) | Shuts down acid production | Squamous ulcers: about 70 to 78% healed at 4 weeks |
| Sucralfate | Coats and protects the glandular lining | Used with omeprazole for glandular ulcers, typically 12 mg/kg twice daily; on its own it was no better than no treatment in the racehorse study |
| Misoprostol | Replaces protective prostaglandins | Glandular ulcers: 72% healed against 20% for omeprazole plus sucralfate in a 2019 trial, though only 12% healed in a later real-world review. Not for pregnant mares, and handlers who are or may be pregnant should wear gloves. |
| Long-acting injectable omeprazole | Weekly intramuscular injection | Glandular ulcers: 80% healed in one study. Not FDA-approved in the US, where it is a compounded product. |
| Ranitidine and other H2 blockers | Reduce acid less completely | Largely replaced by omeprazole; no better than no treatment in the racehorse study |
Sucralfate vs omeprazole? They are not competitors. Omeprazole reduces acid; sucralfate protects the glandular lining. For squamous ulcers, omeprazole alone is the standard. For glandular ulcers, vets often combine the two or switch to misoprostol.
How to Use Ulcer Medication Well: A Practical Protocol
Your vet sets the plan. These steps make it far more likely the tubes you buy actually work.
- Get a scope if you can. Gastroscopy is the only way to know whether ulcers are present, how bad they are, and whether they are squamous, glandular or both. That decides which drug and for how long.
- Use the approved product. GastroGard, UlcerGard or the generic Gastrobim. Skip compounded omeprazole unless your vet has a specific reason.
- Dose by real weight. Use a weight tape. Under-dosing a 1,250 lb horse as if it were 1,000 lb is one of the easiest ways for a course to fail.
- Give it at the same time every day, morning before grain, and make sure it was swallowed.
- Fix the management at the same time. Continuous access to forage, so the stomach is never empty for long. Keep grain meals small; the consensus statement suggests no more than 1 g of starch per kg of body weight per meal. Add some alfalfa, maximize turnout and avoid long stretches of intense work on an empty stomach.
- Review every NSAID. If your horse is on bute or another anti-inflammatory, ask whether it is still needed. NSAIDs are a major cause of glandular ulcers.
- Re-scope at the end of treatment before deciding the job is done, especially for glandular disease.
- Taper, do not stop. Step down to the prevention dose rather than going straight to nothing.
- Use UlcerGard strategically around known stressors, such as hauling, shows, stall rest and training changes, rather than year-round by default.
- Check competition rules. Omeprazole is permitted under FEI rules, but always confirm current rules for your organization.
When to Call Your Vet
- Any sign of colic: pawing, rolling, looking at the flank, lying down more than usual (call immediately)
- A horse that stops eating or leaves grain it normally finishes
- Weight loss or a dull coat despite good feed
- Girthiness, resentment of grooming around the belly, or a change in attitude under saddle
- Recurring mild colic, which the consensus statement links to ulcers in 83% of affected horses
- No improvement after two to three weeks of treatment
- Signs returning soon after a course ends
What About Hemp?
Stress is one of the main drivers of ulcers. That is where owners ask us about hemp.
Hemp is not an ulcer treatment. There is no published study of CBD and gastric ulcers in horses, and anyone who tells you otherwise is guessing. If your horse has ulcers, the treatment is the medication your vet prescribes plus the management changes above.
Where hemp fits is the bigger picture. Stall confinement, hauling, competition and training all raise ulcer risk, and owners managing an ulcer-prone horse are usually managing a stressed one. In a Tarleton State University study of our own equine formula, published as an abstract in the Journal of Animal Science, stereotypic stall behaviors were lower after a single dose of CBD than after the control oil. The same program found no significant change in cortisol during transport, and we report that too. It is early, small-scale evidence on behavior, not on ulcers.
Can you give CBD with omeprazole?
No study has tested CBD and omeprazole together in horses. In people, CBD can inhibit CYP2C19, one of the liver enzymes that clears omeprazole, so it is plausible that CBD could raise omeprazole levels. Whether that happens in horses is unknown. CBD itself is processed by the liver, and in a Colorado State study at higher doses, liver enzymes rose in 8 of 12 horses, all of which improved or normalized within 10 days of stopping. Tell your vet before combining them.
The rule for show horses
CBD is prohibited under USEF, FEI and HISA rules, with no validated withdrawal time. If your horse competes, hemp is off the table during the season. Our guide to CBD safety and show rules has the detail, and our guide to trailering and travel stress covers what is known about hemp and hauling.
How owners actually use it: as a daily top-dress on feed for a non-competing horse that struggles with stall time or travel, started low and judged over two to four weeks, alongside ulcer prevention rather than instead of it. Our horse dosing guide by body weight has the numbers.
The oil studied at Tarleton State University
Equine Formula Hemp Oil · 5,000mg
Organic Colorado hemp in cold-pressed olive oil, top-dressed on feed. About 20mg per half-cc pump. Third-party tested every batch, with the certificate in every order.
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Alternatives to GastroGard
- Gastrobim: the FDA-approved generic omeprazole paste, prescription-only, bioequivalent to GastroGard.
- For glandular ulcers: omeprazole plus sucralfate, misoprostol, or long-acting injectable omeprazole, chosen by your vet.
- For prevention: UlcerGard over the counter during stressful periods.
- Management: constant forage, small starch meals, alfalfa, turnout and limiting NSAIDs do more long-term than any tube.
- Supplements and buffers: many are sold for gastric health. The racehorse study found antacid buffers no better than no treatment, so treat supplements as support, not treatment.
Questions to Ask Your Vet
- Should we scope before treating, and again at the end?
- Are the ulcers squamous, glandular or both, and does that change the drug?
- Is GastroGard or the generic Gastrobim the better value for this horse?
- How should we taper at the end of the course?
- Is my horse's NSAID contributing, and can we reduce it?
- When should I use UlcerGard for prevention, and for how long?
- If I want to add hemp oil for stall or travel stress, is there any reason it would not suit this horse?
Frequently Asked Questions
Which is better, UlcerGard or GastroGard?
Neither is better; they are the same omeprazole paste in the same 2.28 g tube. GastroGard is prescription-only and labeled to treat ulcers at 4 mg/kg daily for 28 days. UlcerGard is over the counter and labeled only to prevent ulcers at about 1 mg/kg. If your horse has ulcers, GastroGard, or its generic Gastrobim, under your vet's direction is the right choice. If your horse is healthy but facing a stressful period, UlcerGard is designed for that.
How often should you give UlcerGard?
Once a day. The label dose is one quarter-tube dose daily for horses 600 to 1,200 lb and two doses for horses over 1,200 lb, for up to 28 days, starting before a stressful event such as hauling, showing or a change in training. In the label study, 82% of horses on UlcerGard stayed ulcer-free under stress, against 14% given a sham dose.
How long does it take UlcerGard or GastroGard to work?
Omeprazole begins suppressing acid within a day or two, and many owners notice better appetite and attitude within one to two weeks. Healing takes longer. Four weeks is the standard checkpoint for squamous ulcers, about 70 to 78% of which heal on treatment. Glandular ulcers heal far less reliably, about 25% at four to five weeks, and the consensus recommendation is at least eight weeks of combined therapy.
Can you buy UlcerGard over the counter?
Yes. UlcerGard is FDA-approved for over-the-counter sale and is available from tack stores, farm stores and online retailers without a prescription. GastroGard and the generic Gastrobim require a prescription from your vet because they are labeled to treat ulcers, which first needs a diagnosis.
How long should a horse be on GastroGard?
The label calls for 28 days at the treatment dose, then at least 28 days at half that dose to prevent recurrence. Safety beyond 91 days has not been determined. Ideally your vet re-scopes at the end of treatment and decides from what they see. Ulcers can return within days of stopping, so taper rather than stop abruptly.
Can I give my horse human omeprazole?
Do not do it without your vet. Human omeprazole capsules are formulated for people, and studies of non-approved omeprazole products in horses found many failed to raise stomach pH or heal ulcers. In a study of 798 racehorses, compounded omeprazole did no better than no treatment. The approved equine pastes are the products with proven absorption and dosing.
What can I use instead of GastroGard?
The FDA-approved generic Gastrobim is the closest substitute. For glandular ulcers, your vet may add sucralfate, switch to misoprostol or use long-acting injectable omeprazole. UlcerGard can be used for prevention. Whatever the drug, constant forage, small starch meals, turnout and limiting NSAIDs are part of every successful plan.
Can you give CBD with omeprazole?
Tell your vet first. No study has tested CBD and omeprazole together in horses. In people, CBD can inhibit CYP2C19, one of the enzymes that clears omeprazole, so an interaction is possible but unproven in horses. CBD raised liver enzymes in 8 of 12 horses at higher doses in one study, all of which normalized after stopping. CBD is prohibited for horses competing under USEF, FEI and HISA rules.
For the stall and travel stress conversation, after your vet has looked
Equine Formula · 5,000mg
Full spectrum · olive-oil base · top-dress on feed
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How Much to Give
Our dosing guide by body weight, with a weight chart and a gentle starting range.
Read the guide →
The Tarleton Research
What the university study on our equine oil found, including what it did not.
See the study →
Grown on our own certified-organic Colorado farm, formulated in-house, third-party tested every batch. See the lab results →
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Marc co-founded HempMy Pet in 2016 with his wife Natalie, the company's COO. HempMy Pet breeds its own hemp genetics, grows them on its certified-organic Colorado farm, and formulates every batch in-house under human-grade standards — seed to sale, nothing sourced overseas. Every batch is third-party tested and the certificates of analysis are published. More about us.
Our own 5,000mg equine formula was the oil studied in a research program at Tarleton State University by Dr. Kimberly Guay, Ph.D., with Trinette Jones, Ph.D. and William B. Smith, Ph.D. In a single-dose study published in the Journal of Animal Science (2021), stereotypic stall behaviors were lower on CBD than on the control oil (P = 0.03), and a dose study recorded no adverse effects at 0.3 or 0.6 mg/kg. The transport-stress arm found no significant change in cortisol, and we report that too. Read what was measured.
Our canine research: HempMy Pet also ran a 90-day study of 37 dogs with chronic joint discomfort, overseen by Dr. Robin Downing, DVM, MS, with Lori Kogan, Ph.D. and Peter W. Hellyer, DVM of Colorado State University. Of the 32 dogs that completed it, 30 (93%) showed a benefit and 94% of owners reported improved quality of life. In 2005 Dr. Downing became only the third veterinarian in the world credentialed as a Diplomate of the American Academy of Pain Management; she founded the International Veterinary Academy of Pain Management and was the AVMA's 2020 Bustad Companion Animal Veterinarian of the Year. See our clinical trials.
This article is general information for horse owners, not veterinary advice. It is reviewed and updated as new peer-reviewed evidence is published, and where the evidence is thin or negative we say so.
How We Sourced This Article
Every figure above comes from one of these. Where we could read the full paper or FDA document we did; where only the abstract is public we used the abstract.
- GastroGard (omeprazole) FDA label and Freedom of Information Summary (NADA 141-123, Boehringer Ingelheim). Supports: dose, duration, tube strength, safety studies and label efficacy figures. FDA Animal Drugs.
- UlcerGard (omeprazole) FDA label and Freedom of Information Summary (NADA 141-227). Supports: prevention dose, over-the-counter status and the 82% vs 14% prevention study. FDA Animal Drugs.
- Sykes BW, Hewetson M, Hepburn RJ, Luthersson N, Tamzali Y. European College of Equine Internal Medicine consensus statement: equine gastric ulcer syndrome in adult horses. Journal of Veterinary Internal Medicine, 2015. PubMed 26340142.
- Varley G, Bowen IM, Habershon-Butcher JL, Nicholls V, Hallowell GD. Misoprostol is superior to combined omeprazole-sucralfate for the treatment of equine gastric glandular disease. Equine Veterinary Journal, 2019. PubMed 30809869.
- Gough S, Hallowell G, Rendle D. Treatment of equine glandular gastric disease with long-acting injectable or oral omeprazole. Veterinary Medicine and Science, 2022. PubMed 35167731.
- Pratt SL, Bowen M, Hallowell GH et al. Does lesion type or severity predict outcome of therapy for equine glandular gastric disease? Veterinary Medicine and Science, 2023. PubMed 36495212.
- Orsini JA, Haddock M, Stine L et al. Odds of moderate or severe gastric ulceration in racehorses receiving antiulcer medications. JAVMA, 2003. PubMed 12906229.
- Nieto JE, Spier S, Pipers FS et al. Comparison of paste and suspension formulations of omeprazole in the healing of gastric ulcers in racehorses. JAVMA, 2002. PubMed 12387383.
- Merritt AM, Sanchez LC, Burrow JA et al. Effect of GastroGard and three compounded oral omeprazole preparations on 24 h intragastric pH in horses. Equine Veterinary Journal, 2003. PubMed 14649361.
- Shan R, Steel CM, Sykes B. Two recommended withholding periods for omeprazole and recurrence of gastric ulcers in Thoroughbred racehorses. Animals, 2023. PubMed 37889700.
- Pagan JD, Petroski-Rose L, Mann A, Hauss A. Omeprazole reduces calcium digestibility in Thoroughbred horses. Journal of Equine Veterinary Science, 2020. PubMed 32067660.
- Tyma JF, Epstein KL, Whitfield-Cargile CM et al. Investigation of effects of omeprazole on the fecal and gastric microbiota of healthy adult horses. American Journal of Veterinary Research, 2019. PubMed 30605038.
- Ricord M, Andrews FM, Yñiguez FJM et al. Impact of concurrent treatment with omeprazole on phenylbutazone-induced equine gastric ulcer syndrome. Equine Veterinary Journal, 2021. PubMed 32697849.
- Busechian S, Di Salvo A, Orvieto S et al. Changes in fitness parameters in showjumping horses after healing of gastric ulcers. Veterinary Sciences, 2025. PubMed 41600665.
- Yocom AF, O'Fallon ES, Gustafson DL, Contino EK. Pharmacokinetics and safety of oral CBD in horses. Journal of Equine Veterinary Science, 2022. PubMed 35307550.
Disclosure: HempMy Pet funded the Tarleton State research on our equine formula and sells the product linked on this page. We had no involvement in any study cited above. Spotted an error? Email support@hempmypet.com and we will correct it.
These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease. This article is general information, not veterinary advice. Never start, stop or change your horse's prescription without your veterinarian.
