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, since collagen adds to the protein you already eat; 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.

Sources checked on 29 October 2026.

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 calls the effective amounts.⁵ The largest daily doses:

None was designed to test safety; that 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.^{1, 2}

Is there an upper limit for collagen in the UK?

No: 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 A serving of collagen counts towards that amount.

What sets a practical ceiling is amino-acid balance. Collagen contains no tryptophan, 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. Collagen as part of your protein sets out the arithmetic.

What happens if you take too much collagen?

In the trials, nothing that separated the collagen groups from the control groups, as the pooled analyses above show.^{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 the 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.¹³ 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 covers the weight studies.

Can too much collagen harm your kidneys?

No trial has reported kidney harm. The 12-month bone trial (131 postmenopausal women, 5 g a day) found "kidney, liver and inflammatory parameters" 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.^{14, 15} Neither publishes a creatinine value; 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.^{16, 17} The NHS kidney-stones page lists "a high-protein, low-fibre diet" among the reasons stones come back, advises 2.5 to 3 litres of water a day, and says "do not make changes to your diet without speaking to your doctor".¹⁸ 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 says to "check with a doctor or pharmacist" before any over-the-counter medicine or nutritional supplement.¹⁹

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-linked 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 supervised training in sarcopenic men 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, 20} 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 per outcome.

What about "too much collagen in the face"?

That phrase is about dermal fillers, an injected cosmetic procedure, and has nothing to do with a supplement: swallowed collagen peptides are digested into amino acids and short peptides, and no serving size changes facial volume.

What are the signs of too much collagen?

The only signs the trial record supports are digestive: fullness, bloating or looser stools after a serving.^{1, 2} Collagen side effects lists who should ask a GP before starting, and is collagen safe when pregnant covers pregnancy.

What we don't know

No trial has set out to find an upper limit for collagen: the pooled safety data come from efficacy trials at 2.5 to 15 g a day, and the 30 to 40 g protocols ran for 4 to 12 weeks in small groups.^{1, 2, 3, 6} No study has measured urinary oxalate on daily peptide doses or counted kidney stones, and none has recruited people with kidney disease.^{16, 17} These are gaps in the evidence, not findings against collagen.

Frequently asked questions

Is it bad to take collagen every day?

Daily use is how every trial ran; the longest 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 an open-label follow-up of 31 of the women recorded four years of daily use.^{14, 4, 21}

Can you overdose on collagen?

No overdose case has been reported in the trial literature, and collagen has no upper limit.¹² A very large serving behaves like any large protein serving: fullness, digestive upset and calories at 4 kcal per gram.¹³

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} 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 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".²² Put collagen on that list.

Sources

1. Liang CW et al. Osteoarthritis and Cartilage, 2024. Pooled analysis, 35 randomised trials, 3,165 people; funding not stated on PubMed. PubMed 38218227
2. Bassila C et al. European Journal of Clinical Nutrition, 2026. Systematic review, 25 randomised trials; one consultancy-employed author, no funding stated. PubMed 42342959
3. Alipoor E et al. Clinical Nutrition, 2023. Randomised trial, 66 burns patients, 4 weeks; no conflicts declared. PubMed 36724726
4. Mertz KH et al. American Journal of Clinical Nutrition, 2021. Randomised trial, 208 adults over 65, 1 year; funding not stated on PubMed. PubMed 33564844
5. Paul C, Leser S, Oesser S. Nutrients, 2019. Dietary modelling study; one author consults for a supplement manufacturer. PubMed 31096622
6. Nulty CD, Phelan K, Erskine RM. European Journal of Sport Science, 2025. Randomised trial, 20 men, 12 weeks; no conflicts declared. PubMed 40100255
7. Nulty CD, Erskine RM. International Journal of Sport Nutrition and Exercise Metabolism, 2025. Randomised trial, 22 women, 8 weeks; funding not stated on PubMed. PubMed 40992424
8. Lee J, Robshaw DC, Erskine RM. Experimental Physiology, 2025. Randomised trial, 11 professional footballers, 10 weeks; no conflicts declared. PubMed 39207908
9. Clifford T et al. Amino Acids, 2019. Randomised trial, 24 men, 9 days; two supplier-employed authors. PubMed 30783776
10. Zdzieblik D et al. British Journal of Nutrition, 2015. Randomised trial, 53 sarcopenic men, 12 weeks; part supplier-funded, with supplier-linked authors. PubMed 26353786
11. Sugihara F et al. Scientific Reports, 2018. Randomised trial, 120 people with pressure ulcers, 16 weeks; manufacturer-funded. PubMed 30061579
12. Public Health England. Government dietary recommendations, Table 2. Read 29 October 2026. gov.uk
13. Retained Regulation (EU) No 1169/2011, Annex XIV (conversion factors for energy). Read 29 October 2026. legislation.gov.uk
14. König D et al. Nutrients, 2018 (section 3.5, safety parameters). Randomised trial, 131 postmenopausal women, 12 months; no conflicts declared. PubMed 29337906
15. Duangjai A et al. Clinics and Practice, 2025. Randomised trial, menopausal women in four groups, 6 months; no conflicts declared. PubMed 41002783
16. Knight J et al. Kidney International, 2006. Controlled-diet study in healthy volunteers; funding not stated on PubMed. PubMed 17021603
17. Rodgers A et al. International Urology and Nephrology, 2019. Laboratory study, 5 healthy men, 3 days; funding not stated on PubMed. PubMed 31161522
18. NHS. Kidney stones. Page last reviewed 17 September 2026. nhs.uk
19. NHS. Chronic kidney disease: living with. Page last reviewed 22 March 2023 (review overdue). nhs.uk
20. Bischof K et al. Sports Medicine, 2024. Pooled analysis, 19 randomised trials, 768 adults; no external funding. PubMed 39060741
21. Zdzieblik D, Oesser S, König D. Journal of Bone Metabolism, 2021. Open-label four-year follow-up, 31 women; supplier-linked author. PubMed 34520654
22. NHS. Having surgery: preparation. Page last reviewed 9 July 2024. nhs.uk

Spotted something out of date? Email support@wellgard.co.uk with the page address and the sentence.

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.