Quick answer: Nutramax's label for Cosequin DS lists no specific side effects, but it does warn that "overconsumption may be harmful", so the flavoured tablets need to be stored out of your dog's reach. Direct-Vet, which sells it to UK buyers, notes that some dogs get mild digestive upset when they start, which giving it with a meal may help. We found no UK reviews reporting side effects, but there are hardly any UK reviews at all, and the label doesn't name its flavourings or say where its glucosamine comes from. If Cosequin hasn't suited your dog, we'd recommend trying MedPaw Hip & Joint Chews instead, 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. Cosequin's label details come from UK retailer listings and Nutramax's published label, because the UK Cosequin website blocked our access. Everything was checked on 8 October 2026.
What Cosequin's label says
Cosequin is a supplement, not a medicine, so it doesn't come with a list of side effects like a prescription drug. Here's what the label and UK listings do say:
- Overconsumption: "Keep product securely stored, as overconsumption may be harmful" (Nutramax's label for Cosequin DS chewable tablets, published on Drugs.com). The tablets are flavoured, so keep the tub somewhere your dog can't get at it.
- Dogs only: the same label says "Product only intended for dogs."
- Medical conditions: "If your pet has any condition that requires medical attention, you should always consult your veterinarian."
- Starting out: Direct-Vet says some dogs may have mild digestive upset at first, and giving it with a meal may help.
- Dose: the loading phase lasts 4 to 6 weeks, at up to four tablets a day for dogs over 50kg. Your dog gets the most during that phase, so that's when to watch closely.
- Pregnancy, nursing and medication: we found no specific guidance on the UK listings. Ask your vet first.
What owners actually report
Very little, in the UK. VetUK's Cosequin DS listing has no reviews, and the two reviews on Direct-Vet are both positive and don't mention side effects. We couldn't read reviews on Costco UK or Amazon UK.
Side effects in the UK Cosequin reviews we could read (2 reviews)
| Reported effect | How often | Notes |
|---|---|---|
| Upset stomach, diarrhoea or vomiting | None found | Direct-Vet says mild digestive upset can happen when starting |
| Itching or skin reaction | None found | Flavourings and glucosamine source aren't stated |
| Refusing the tablet | None found | Too few reviews to judge |
Two reviews can't tell you how common side effects are. That's the real problem: with so little UK feedback, you're judging Cosequin mostly on the label. For the wider picture, see our Cosequin reviews.
Cosequin allergens and ingredients to check
We couldn't find an allergen statement for Cosequin DS. Based on Nutramax's label (glucosamine hydrochloride, sodium chondroitin sulphate, manganese ascorbate, microcrystalline cellulose, natural and artificial flavors, silicon dioxide):
Common allergens in Cosequin DS chewable tablets
| Allergen | In Cosequin DS? |
|---|---|
| Chicken, beef or pork | Not named; the flavourings aren't specified |
| Shellfish | Not listed, but the source of the glucosamine isn't stated |
| Fish, krill or mussel | Not listed |
| Egg | Not listed |
| Cereals or gluten | Not listed |
Different versions of Cosequin are sold in the UK, including imported US formulas with MSM, and their ingredients differ. If your dog has a food allergy, check the box you actually receive. For more, see what's in Cosequin.
When to stop and call your vet
- Vomiting or diarrhoea that lasts more than a day, or blood in either
- Your dog goes off their food or becomes lethargic
- Itching, hives, facial swelling or breathing trouble (call straight away)
- Your dog has eaten a lot of tablets at once (the label warns overconsumption may be harmful)
- Your dog is on other medicines, is diabetic, pregnant or nursing, or has a known food allergy
Any supplement can upset some dogs' stomachs, including ours. For more, read our general guide to joint supplement side effects in dogs.
Why Cosequin customers switch to MedPaw
We'll be straight: MedPaw contains mollusc (green-lipped mussel) and gluten (brewer's yeast), and it's a chicken and bacon flavour chew, so it isn't the answer for every allergy. Where it differs is in how clearly it's labelled, what's in it and what happens if it doesn't suit.
Cosequin vs MedPaw
| The issue | Cosequin DS | MedPaw |
|---|---|---|
| If it doesn't suit your dog | No money-back guarantee we could find | 60 days from delivery, for any reason; email us and keep the tub |
| Knowing the flavour | "Natural and artificial flavors", not named | Chicken and bacon flavour |
| Allergens | No allergen statement found | Contains mollusc and gluten; not suitable for a shellfish allergy |
| Time on the higher dose | 4 to 6 weeks, up to four tablets a day | Three weeks |
| What's in it | Glucosamine, chondroitin, manganese | All six key joint actives (glucosamine, chondroitin, MSM, green-lipped mussel, hyaluronic acid, Boswellia), with the main amounts per chew on the label |
Our recommendation: if Cosequin upset your dog's stomach, you're unsure what's in the flavouring, or you want a guarantee before you try something new, switch to MedPaw, as long as your dog has no shellfish or gluten allergy. Wait until any upset has settled, then start MedPaw. If it doesn't suit, email bark@medpaw.co.uk within 60 days of delivery for a refund. 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 Cosequin: MedPaw vs Cosequin, why Cosequin might not be working and our Cosequin vs Dasuquin guide.
Does Cosequin have side effects?
Nutramax's label lists no specific side effects, but warns that overconsumption may be harmful. Direct-Vet, which sells it to UK buyers, says some dogs get mild digestive upset when they start, and giving it with a meal may help. We found no UK reviews reporting side effects, though there are very few UK reviews.
Can Cosequin cause diarrhoea?
Mild digestive upset is possible when starting, according to Direct-Vet, which sells it to UK buyers. If your dog has diarrhoea for more than a day after starting Cosequin, stop it and speak to your vet.
What if my dog ate a lot of Cosequin tablets?
Call your vet. Nutramax's label warns that overconsumption may be harmful and says to keep the product securely stored. Have the tub to hand so you can tell them how many tablets are missing.
Is Cosequin safe for dogs with a shellfish allergy?
We couldn't confirm it. The label doesn't list shellfish, but it doesn't say where the glucosamine comes from or name its flavourings. Ask your vet first. MedPaw contains green-lipped mussel, so it isn't suitable for a shellfish allergy either.
What should I try if Cosequin upset my dog?
Let your dog's stomach settle first and speak to your vet if it doesn't. Then you could try MedPaw Hip & Joint Chews, a soft chew with all six key joint actives and a 60-day money-back guarantee. It contains mollusc and gluten, so it isn't suitable for dogs with a shellfish or gluten allergy.
Can I switch from Cosequin to MedPaw straight away?
Yes, if your dog is well. Stop Cosequin and start MedPaw the next day, and don't give both. If Cosequin upset your dog's stomach, wait until it has settled first. Check with your vet if your dog takes any medication.
