Can You Take Too Much Collagen? Upper Doses in the Trials

There is no UK upper limit for collagen, because collagen is a protein and the government's dietary recommendations give protein as a daily amount to reach, not a ceiling. Across 35 randomised trials in 3,165 people, collagen did not increase side effects or drop-outs against the control groups, and the trials that used the most gave 30 g a day for tendons, 40 g a day in burns care and 20 g twice a day for a year in adults over 65.^{1, 2, 3, 4} "Too much" is a protein question: collagen lacks tryptophan, so it adds to the protein you already eat, and up to about a third of a day's protein can be collagen peptides.⁵ Two groups keep to a moderate serving and ask a GP first: people who form calcium-oxalate kidney stones and anyone on a protein-restricted diet for kidney disease. This page sits beneath the Wellgard collagen guide.

What is the highest dose of collagen used in trials?

Most collagen trials used 2.5 to 15 g a day, the range a 2019 analysis describes as the effective amounts in the literature.⁵ The largest daily doses, the trial each came from and what it measured:

None of these trials was designed to test safety. That finding comes from the pooled analyses: the 2024 analysis of 35 osteoarthritis trials found no increase in adverse events or withdrawals against control, and a 2026 systematic review of 25 skin trials recorded a low incidence of adverse events across the set.^{1, 2}

Is there an upper limit for collagen in the UK?

No. The UK has no upper limit for collagen or for protein. The government's dietary recommendations list protein as a daily amount to reach, 55.5 g for a man and 45 g for a woman aged 19 to 64, and attach a "less than" figure to fat, saturated fat, sugars and salt but not to protein.¹² The NHS Eatwell advice (reviewed 30 June 2026) is to "eat some beans, pulses, fish, eggs, meat and other protein".¹³ A serving of collagen counts towards that amount.

What sets a practical ceiling is amino-acid balance. Collagen contains no tryptophan, which is why protein-quality scores class it as incomplete, and the 2019 calculation found that up to 36% of a day's protein can be collagen peptides with the indispensable amino acids still met.⁵ On the 45 g recommendation that is roughly 16 g of collagen a day; on 55.5 g, roughly 20 g; anyone eating more protein has more room. Collagen as part of your protein sets out the arithmetic: the rest of the day's protein decides what "too much" is.

What happens if you take too much collagen?

In the trials, nothing that separated the collagen groups from the control groups: adverse events and withdrawals were no more frequent across 35 trials, and the 25 skin trials recorded a low incidence of adverse events.^{1, 2} The usual report with a large serving of any protein is digestive, fullness, bloating or looser stools, which settles with a smaller serving or food; collagen and digestion covers those steps.

Calories are the other half. UK food labels count protein at 4 kcal per gram, so 10 g of collagen is about 40 kcal and 20 g about 80 kcal.¹⁴ In the 15 g muscle trial, fat mass fell more in the collagen group than in the control group, both of whom trained.¹⁰ Does collagen help with weight loss sets out what the weight studies measured.

Can too much collagen harm your kidneys?

No trial has reported kidney harm. The 12-month bone trial of 5 g a day in 131 postmenopausal women reported that blood safety parameters, "kidney, liver and inflammatory parameters" among them, "showed no clinically relevant changes", and a six-month trial of 5 g of fish collagen in menopausal women reported serum creatinine, ALT and AST within normal ranges.^{15, 16} Neither publishes a creatinine value, and no trial has recruited people with kidney disease, so no page can say "safe for your kidneys"; is collagen bad for your kidneys or liver sets out the trial record.

Two cautions are real. First, collagen is rich in hydroxyproline, which the body partly converts to oxalate: a 30 g gelatine load raised urinary oxalate by 43% against whey in one study, with changes at 5 and 10 g loads but not at 1 and 2 g, while five men on 30 g of gelatine for three days showed no change in oxalate.^{17, 18} Neither measured stones. The NHS kidney-stones page (reviewed 17 September 2026) lists "a high-protein, low-fibre diet" among the reasons stones come back, advises 2.5 to 3 litres of water a day for an adult, and says "do not make changes to your diet without speaking to your doctor".¹⁹ For a calcium-oxalate stone former, that means a moderate daily serving and a GP conversation. Second, anyone on a protein-restricted diet for chronic kidney disease counts collagen as protein; the NHS CKD page (reviewed 22 March 2023, past its March 2026 review date) says to "check with a doctor or pharmacist" before taking any over-the-counter medicine or nutritional supplement.²⁰

Can you take 20 g of collagen a day?

20 g a day sits inside the range trials have used: it was the dose in the nine-day supplier-funded recovery trial, where jump height recovered faster at 48 hours in the collagen group, and half the daily amount in the year-long muscle trial.^{4, 9} The 15 to 30 g protocols were built for training: 15 g a day with three supervised sessions a week in sarcopenic men, in a part supplier-funded trial, increased fat-free mass by 4.2 kg against 2.9 kg, and the 2024 pooled analysis of 19 training trials found a moderate-certainty gain in fat-free mass.^{10, 21} The skin, joint and bone trials used 2.5 to 15 g, so 20 g is a training dose rather than a skin dose; how much collagen to take a day gives the dose for each outcome.

What about "too much collagen in the face"?

That phrase is about dermal fillers, an injected cosmetic procedure that adds volume under the skin, and it has nothing to do with a supplement. Swallowed collagen peptides are digested into amino acids and short peptides; no serving size changes facial volume. Questions about fillers belong with a registered practitioner.

What are the signs of too much collagen?

The only signs the trial record supports are the digestive ones: fullness, bloating or looser stools after a serving.^{1, 2} Take a smaller serving or take it with food, and mention them to a GP if they persist. Collagen side effects lists who should ask a GP before starting, and is collagen safe when pregnant covers pregnancy, where there are no trials and the route is the midwife or GP.

Frequently asked questions

Is it bad to take collagen every day?

Daily use is how every trial ran. The longest randomised trials ran for a year, 5 g a day in 131 postmenopausal women with no adverse events noted and 20 g twice a day in 208 adults over 65, and a supplier-linked open-label follow-up of 31 of the women recorded four years of daily use.^{15, 4, 22} Nothing longer has been studied.

Can you overdose on collagen?

No overdose case has been reported in the trial literature, and collagen has no upper limit because it is a protein.¹² A very large serving behaves like a large serving of any protein: fullness, digestive upset and calories at 4 kcal per gram.¹⁴ The amount matters for stone formers and people on restricted protein, as above.

Can I take collagen twice a day?

Yes. The pressure-ulcer trial gave 10 g a day as two 5 g servings for 16 weeks, and the year-long muscle trial gave 20 g twice a day.^{4, 11} Splitting does not change the grams; when should I take collagen covers timing.

Should I stop collagen before surgery?

No interaction between collagen peptides and any medicine, anaesthetics included, has been documented. The NHS pre-operative advice (reviewed 9 July 2024) is to make sure you know "all the medicines, vitamins and herbal supplements you take", and the hospital tells you "whether you should stop taking your usual medicines before going into hospital".²³ Put collagen on that list and follow the team's instruction.

Sources

1. Liang CW et al. Osteoarthritis and Cartilage, 2024. PubMed 38218227
2. Bassila C et al. European Journal of Clinical Nutrition, 2026. PubMed 42342959
3. Alipoor E et al. Clinical Nutrition, 2023. PubMed 36724726
4. Mertz KH et al. American Journal of Clinical Nutrition, 2021. PubMed 33564844
5. Paul C, Leser S, Oesser S. Nutrients, 2019. PubMed 31096622
6. Nulty CD, Phelan K, Erskine RM. European Journal of Sport Science, 2025. PubMed 40100255
7. Nulty CD, Erskine RM. International Journal of Sport Nutrition and Exercise Metabolism, 2025. PubMed 40992424
8. Lee J, Robshaw DC, Erskine RM. Experimental Physiology, 2025. PubMed 39207908
9. Clifford T et al. Amino Acids, 2019. Supplier-funded. PubMed 30783776
10. Zdzieblik D et al. British Journal of Nutrition, 2015. Part supplier-funded. PubMed 26353786
11. Sugihara F et al. Scientific Reports, 2018. PubMed 30061579
12. Public Health England. Government dietary recommendations, Table 2. Read 12 October 2026. gov.uk
13. NHS. Eating a balanced diet (reviewed 30 June 2026). nhs.uk
14. Retained Regulation (EU) No 1169/2011, Annex XIV (conversion factors for energy). Read 12 October 2026. legislation.gov.uk
15. König D et al. Nutrients, 2018 (section 3.5, safety parameters). PubMed 29337906
16. Duangjai A et al. Clinics and Practice, 2025. PubMed 41002783
17. Knight J et al. Kidney International, 2006. PubMed 17021603
18. Rodgers A et al. International Urology and Nephrology, 2019. PubMed 31161522
19. NHS. Kidney stones (reviewed 17 September 2026). nhs.uk
20. NHS. Chronic kidney disease: living with (reviewed 22 March 2023). nhs.uk
21. Bischof K et al. Sports Medicine, 2024. PubMed 39060741
22. Zdzieblik D, Oesser S, König D. Journal of Bone Metabolism, 2021 (four-year open-label follow-up; supplier-linked). PubMed 34520654
23. NHS. Having surgery: preparation (reviewed 9 July 2024). nhs.uk

This article is general information, not medical advice. If you form kidney stones, have kidney disease, are pregnant or are preparing for an operation, speak to your GP or care team before adding any supplement.