Can Collagen Cause Bloating? Check the Dose on Your Tub First
Tim GoodwinYes, it can. If you have only just started, the most likely reason is printed on the back of your own tub.
Most people blame the collagen itself. Usually it is the dose.
Collagen powders sold in the UK direct you to take anywhere from 3g to 20g a day. That is a very wide range for what looks like the same product on the shelf. If you bought one from the top of it, you are taking a lot of dense protein in one go.
Here is how to check yours, and what to do about it.
Related reading
Check your own tub, in about 30 seconds
Go and get it. There are three things to look for.
1. How many grams a day does it tell you to take?
Look for "daily portion" or the directions. This is the number that matters most, and it is the one that varies most between brands.
2. Does it say hydrolysed peptides?
Hydrolysed means the protein has already been broken into shorter pieces. Nearly every UK collagen powder is hydrolysed and says so on the tub.
3. Is there sorbitol, xylitol or maltitol in the ingredients?
These are sugar alcohols and they are a well known cause of gas and bloating. They turn up in flavoured products.
For most UK tubs, the second answer is yes and the third is no. That leaves the dose. So start there.
What UK collagen powders tell you to take
We checked the directions on four collagen products sold in the UK in August 2026, plus our own.
| Product | Collagen a day | Price | Days in a pack |
|---|---|---|---|
| Vital Proteins Collagen Peptides, 284g | 20g, or 2 scoops | £29.99 at Boots | About 14 |
| Holland & Barrett Bovine Collagen, 150g | 5g, or 1 scoop | £24.99 | 30 |
| Boots High Strength Skin Formula, 151.5g | 5g, or 2 teaspoons | £18.00 | 30 |
| Wellthy by Boots Skin Glow sachets | 3g | £18.00 | 30 |
| Collagen Greens (ours) | 4g | £47.00 a month | 33 |
Prices and directions taken from each product's own listing on 13 August 2026. Prices change constantly, so check before you buy.
Look at the top row against the rest. Vital Proteins is one of the best selling collagen powders in Britain, and it directs four times the dose of the Holland & Barrett tub.
Neither is wrong. But if you switched brands, or bought your first tub without comparing, you may be taking far more than you think.
How much collagen do the studies actually use?
Less than you might expect.
Holland & Barrett say this on their own collagen listing. They cite two randomised trials using 2,500mg a day for six to eight weeks. They class that as moderate evidence, and say more research is needed.
That is 2.5g. The market leading tub directs eight times as much.
We are not going to tell you that a bigger dose does nothing, because that is not settled either. Studies on collagen have used a wide range. The point is narrower and more useful. If the amount on your tub is making you uncomfortable, taking less is not obviously giving something up.
Two explanations you will read everywhere that do not fit UK tubs
Search this question and you will get the same two answers over and over. We checked both against the ingredients lists of the collagen powders actually sold here, and neither holds up well.
"Your collagen isn't hydrolysed"
The claim is that cheap collagen is really gelatin, so your gut has to do all the work.
It is not what the labels say. Holland & Barrett's own tub lists "Hydrolysed Bovine Collagen, Vitamin C" and nothing else. Vital Proteins lists "Bovine collagen peptides" and nothing else. Both are already broken down.
"It's the sugar alcohols"
Sugar alcohols genuinely do cause bloating. The problem is finding any in a UK collagen powder.
We read the ingredients on four of them. Boots' is two ingredients. Holland & Barrett's is two ingredients. Vital Proteins is one. Not one contained sorbitol, xylitol or maltitol.
They are worth checking for if yours is flavoured, and they are a real problem in some flavoured protein products. On the plain collagen most people buy, they are not the answer.
An earlier version of this page leaned on both of those explanations. We went and read the labels, found they did not match, and rewrote it. We would rather say that than quietly change it.
What does still fit
Three things, none of them dramatic.
The size of the hit. 20g of protein in one glass, on an empty stomach, is a real load. Protein slows how fast the stomach empties. That is usually a good thing, and it can also feel like heaviness.
No fibre alongside it. Plenty of people take collagen in black coffee first thing. There is nothing in that to keep things moving.
Your own digestion. How well anyone breaks down a big protein load varies, and it varies day to day. This is the explanation people reach for most, and it is also the hardest one to check on yourself.
What to try, cheapest first
None of the first four costs anything.
- Halve the scoop for a week. If your tub directs 20g, take 10g. This is the single most likely fix and it makes your tub last twice as long.
- Take it with food. Not on an empty stomach, and not in black coffee.
- Split it. Half in the morning, half later, rather than the lot at once.
- Give it two weeks. Some people settle. If it is getting worse rather than better, stop.
- Then look at the product. If a smaller dose taken with food still bothers you, the powder may not suit you, and there is no prize for pushing through.
When it is not the collagen
This one matters more than anything else on the page.
Bloating that carries on for weeks, or comes with weight loss, blood, pain or a change in your bowel habits, is not a supplement question. See your GP.
Collagen is the new thing you started, so it gets the blame. That does not make it the cause. Nothing here is medical advice, and a persistent symptom deserves a proper look rather than a blog post.
Where our product fits, and where it does not
We sell a greens powder with collagen in it, so read this part knowing that.
Collagen Greens has 4g of hydrolysed bovine collagen peptides per scoop. That is a small dose by the standards of the shelf above. It sits alongside greens, which bring some fibre, and a multi-enzyme complex called DigeZyme plus bromelain, which are there to work on protein.
We are not going to promise you that stops bloating. What we will say is what is in it and what it is not.
It is not the answer if you want a big collagen dose. If you are after 10g or more, buy a dedicated collagen powder. Holland & Barrett's is 83p a day and Boots' is 60p a day, and both are cheaper than us.
It is not the answer if the fix is just taking less. If halving your existing scoop sorts it, do that and keep your money. That is genuinely the first thing to try.
Where we do fit is narrower. Some people want a modest collagen dose that arrives with greens and enzymes rather than on its own. One drink instead of three. That is what we make.
IF YOU WANT A SMALLER DOSE
4g of collagen, with the greens
Hydrolysed bovine collagen peptides at 4g a scoop, alongside a greens blend, DigeZyme multi-enzyme complex and bromelain. No sugar alcohols, no flavouring. One drink instead of three tubs.
60-day money-back guarantee.
Trusted by 20,000+ UK customers since 2012.
The short version
Yes, collagen can cause bloating.
Check the dose on your tub before you blame the collagen. UK products range from 3g to 20g a day, and the trials Holland & Barrett cite used 2.5g.
Halve it, take it with food, give it a week. If that fixes it, you have solved the problem for nothing.
Questions people ask
How much collagen should I take a day?
UK products direct anywhere from 3g to 20g. Holland & Barrett cite trials using 2,500mg a day for six to eight weeks and call that moderate evidence. If your current dose is causing problems, taking less is a reasonable first step.
Does hydrolysed collagen cause less bloating?
It is already broken into shorter peptides, so it is easier to digest than gelatin. The catch is that almost every collagen powder sold in the UK is already hydrolysed. Check your label, but it is unlikely to be your problem.
Should I take collagen on an empty stomach?
You do not have to, and if it bloats you, try not to. Taking it with food and with something containing fibre is a simple change worth a week's trial.
Which collagen powder is least likely to bloat me?
The honest answer is a smaller dose of whatever you already own. If you are buying fresh, the lower dose products on UK shelves are Wellthy by Boots at 3g and our own Collagen Greens at 4g. Holland & Barrett and Boots both direct 5g.
How long does collagen bloating last?
For most people it settles within a week or two, or it improves as soon as the dose comes down. If it is still there after that, or getting worse, stop taking it and speak to your GP.
Can collagen cause constipation as well as bloating?
Some people report it, usually alongside a low fibre diet and not much water. We covered that separately in can collagen powder cause constipation.