Quick answer: Antinol says adverse reactions are rare but may include gastrointestinal disturbances, such as an upset stomach. It shouldn't be given to dogs with a known shellfish allergy, and the capsule is made from beef gelatin. In the roughly 130 Antinol reviews we read, one owner reported diarrhoea and sickness; the more common problems were dogs refusing the capsule and seeing no difference. If Antinol hasn't suited your dog, we'd recommend trying MedPaw Hip & Joint Chews instead: a soft chew given like a treat, with a 60-day money-back guarantee if it doesn't suit.
Transparency note: this page is written by MedPaw, which makes a competing joint supplement. Reviews are quoted word for word with links so you can check them. Antinol's label, help centre and reviews were checked on 8 October 2026. This page isn't veterinary advice; if you're worried about your dog, call your vet.
What Antinol says about side effects
Antinol Joint Care Pro is a softgel capsule containing 50mg of PCSO-524, an oil extract of New Zealand green-lipped mussel, in olive oil with glycerin and vitamin E. Here's what Antinol's own product page and help centre say:
- Reactions are rare. "Adverse reactions to Antinol® are rare but may include gastrointestinal disturbances" (Antinol help centre).
- Shellfish allergy. Antinol asks you not to give it to a pet you know is allergic to shellfish.
- Beef allergy. The capsule is beef gelatin. For a beef-allergic pet, Antinol suggests piercing the capsule and squeezing the oil onto food instead.
- Other medicines. The product page says there are no known side effects or unfavourable interactions with other medications, and that it can be given alongside anti-inflammatory painkillers (NSAIDs), but to speak to your vet first.
- Other fish or marine oils. Antinol advises against giving other omega-3 or marine oils at the same time.
- Pregnancy and lactation. We couldn't find any guidance on pregnant or nursing dogs on the product page or help centre. Ask your vet before giving it.
What owners actually report
We read around 130 Antinol reviews on Trustpilot, from October 2023 to August 2026. Reports of reactions were rare. Frequencies are our estimates from that sample.
Reactions and problems in Antinol reviews (our sample)
| What was reported | How often | What reviewers said |
|---|---|---|
| Diarrhoea and sickness | One review | A dog that couldn't tolerate it |
| Refusing the capsule | A few reviews, mostly about cats | Pets refusing it, even hidden in food |
| Capsules harder to give | One review | Newer capsules felt firmer to cut open |
| Itching or skin reactions | None found | No reports in the reviews we read |
The one clear reaction report came, unusually, in a five-star review: "Order was promptly delivered but unfortunately my poor dog couldn't tolerate it and was very ill with diarrhoea and sickness" (Carolyn D., 5 stars, October 2024).
Refusing the capsule isn't a side effect, but it's the more common problem: "My dog would not take them given suggested other ways of giving her them" (Jean S., 4 stars, September 2024). Another owner said the "new capsules are harder" and "I need to make a hole in the capsules." (Alberta, 4 stars, August 2024).
For the wider picture, including complaints about results and delivery, read our Antinol reviews and complaints page.
Allergens in Antinol
Antinol Joint Care Pro allergen check (published ingredients)
| Allergen | In Antinol? |
|---|---|
| Shellfish (green-lipped mussel) | Yes, it's the active ingredient |
| Beef | Yes, the capsule is beef gelatin |
| Fish or krill oil | Not listed |
| Chicken | Not listed |
| Egg | Not listed |
| Gluten or grains | Not listed |
To be fair about our own product: MedPaw also contains mollusc (green-lipped mussel), so it isn't suitable for a dog with a shellfish allergy either, and it contains gluten from brewer's yeast. Any supplement can upset some dogs' stomachs, MedPaw included.
When to stop and call your vet
Stop giving Antinol and call your vet if your dog has:
- Vomiting or diarrhoea that doesn't settle within a day, or any blood in either
- Swelling of the face, hives or any difficulty breathing (this is an emergency)
- Lethargy, or going off their food for more than a day
- A stomach upset while also taking an anti-inflammatory painkiller, as these medicines can upset the stomach too
Once your dog is back to normal, talk to your vet before trying any new supplement. Our general guide to joint supplement side effects in dogs covers what to watch for with other ingredients.
Why Antinol customers switch to MedPaw
Antinol vs MedPaw if Antinol didn't suit your dog
| The issue | Antinol | MedPaw |
|---|---|---|
| Won't take capsules | Softgel capsule, or pierce and squeeze onto food | Soft chicken and bacon flavour chew, given from your hand like a treat |
| Wanting a different formula | Green-lipped mussel oil only | All six key joint actives, with the main amounts per chew on the label: MSM 185mg, glucosamine 170mg, chondroitin 70mg, green-lipped mussel 70mg, Boswellia 30mg, plus hyaluronic acid |
| If it doesn't suit | 60-day trial on Starter Packs for new customers | 60 days from delivery, for any reason; email us and keep the tub |
Our recommendation: if your dog wouldn't take Antinol's capsules, or you'd like a different formula once any upset has settled, try MedPaw. Swap rather than stack, and if it doesn't suit your dog, email us within 60 days for a refund with nothing to send back. Try MedPaw Hip & Joint Chews.
If nothing has worked so far
If your dog is still stiff or sore after a fair trial of any supplement, see your vet. They may suggest pain relief, weight loss or an omega-3 fish oil at a proper dose, which has the strongest evidence for dogs with arthritis. Read what you can safely give a dog for joint pain and the best fish oil for dogs' joints.
More on Antinol: Antinol ingredients explained, MedPaw vs Antinol and Antinol vs green-lipped mussel powder.
Does Antinol have side effects?
Antinol says adverse reactions are rare but may include gastrointestinal disturbances. In the reviews we read, one owner reported diarrhoea and sickness. It shouldn't be given to dogs with a known shellfish allergy.
Can Antinol cause diarrhoea?
It can in some dogs. Antinol lists gastrointestinal disturbances as a possible, rare reaction, and one owner in the reviews we read said their dog was very ill with diarrhoea and sickness. If diarrhoea doesn't settle within a day, stop and call your vet.
Is Antinol safe for dogs with a shellfish allergy?
No. Antinol is made from green-lipped mussel and asks you not to give it to pets known to be allergic to shellfish. MedPaw also contains green-lipped mussel, so it isn't suitable either.
Does Antinol contain beef?
The capsule is made from beef gelatin. Antinol suggests piercing it and squeezing the oil onto food for pets with a beef allergy.
Can Antinol be given with painkillers?
Antinol says it can be given alongside anti-inflammatory painkillers (NSAIDs) but to speak to your vet first. It also advises against giving other omega-3 or marine oils at the same time.
Can I switch from Antinol to MedPaw?
Yes, once any stomach upset has settled. Stop Antinol and start MedPaw; don't give both. Check with your vet first if your dog takes any medication or has had a reaction.
