Is there a downside to taking collagen powder? Unpacking the risks and side effects

October 15, 2025 •

5 min read

With the global collagen supplement market booming, many people are adding collagen powder to their daily routine. However, amidst the promised benefits for skin and joints, a common question arises: is there a downside to taking collagen powder? While generally safe for most, there are potential side effects, risks, and regulatory gaps that consumers should be aware of before purchasing.

Quick Summary

Collagen powder can cause digestive upset, allergic reactions related to its source, or an unpleasant taste. Users also face risks of heavy metal contamination and potential kidney stone formation. Quality control is not federally regulated, necessitating careful product selection and consultation with a healthcare provider.

Key Points

Digestive Upset: Some users experience bloating, gas, nausea, and heartburn, especially with higher doses or certain formulations.
Heavy Metal Risk: Due to a lack of FDA regulation, some collagen powders have been found to contain concerning levels of heavy metals like lead and cadmium.
Kidney Stone Potential: The amino acid hydroxyproline in collagen can be converted into oxalate, posing a risk of kidney stone formation for susceptible individuals.
Allergic Reactions: Collagen is sourced from animals (bovine, marine), so those with related allergies (e.g., fish, shellfish) are at risk of a reaction.
Inconsistent Regulation: The supplement industry is not tightly regulated by the FDA, making third-party verification essential for ensuring product purity and safety.
Not a 'Magic Bullet': While some studies show benefits, they are often inconsistent, and a balanced diet with essential amino acids can also support natural collagen production.

Common side effects of collagen powder

While many people tolerate collagen powder without issue, some experience mild to moderate side effects. These are often associated with larger doses or sensitivities to certain ingredients. The most frequently reported issues involve digestive discomfort.

Digestive upset

For some individuals, particularly those with sensitive stomachs, collagen supplements can cause gastrointestinal issues. These can include:

Bloating and gas
A feeling of fullness or heaviness in the stomach
Heartburn
Nausea
Mild diarrhea or constipation

In some cases, these digestive troubles are linked to the supplement's form. High-quality, hydrolyzed collagen is broken down into smaller peptides that are generally easier for the body to absorb. Poorly hydrolyzed or gelatin-based forms may be harder to digest, leading to these symptoms. Additionally, some supplement blends contain other active ingredients, like biotin, which can cause digestive distress if taken in excess.

Unpleasant taste

Some users report that collagen supplements leave a lingering, unpleasant aftertaste in their mouth, which can make consistent use challenging. This is particularly common with marine-sourced collagen, which can have a faint, fishy flavor. Opting for unflavored bovine or high-quality marine collagen, or mixing it into strongly flavored beverages, may help mitigate this issue.

Rashes and skin reactions

Although rare, some people may experience skin-related reactions, such as rashes, hives, or itching. This is often an allergic response to the source material of the collagen (e.g., fish, shellfish, or bovine) or other additives in the supplement. It's crucial to check the product's source if you have known allergies.

More serious risks of taking collagen powder

Beyond the minor and temporary side effects, there are more significant concerns to consider, including potential contaminants and health complications for certain individuals.

Heavy metal contamination

One of the most concerning downsides is the risk of heavy metal contamination. Since collagen is derived from animal parts like bones and hides, environmental pollutants like arsenic, lead, cadmium, and mercury can accumulate in the raw materials. A 2019 report by the Clean Label Project tested 30 collagen products and found that 37% contained detectable levels of lead, and 17% contained cadmium. Some of these levels exceeded California's Proposition 65 limits. The lack of federal regulation for supplements means brands are not required to test for and prove their product's purity. To mitigate this risk, consumers must choose high-quality products that provide transparent, third-party testing results.

Increased risk of kidney stones

Collagen contains the amino acid hydroxyproline. When the body breaks this down, it can convert it into oxalate, a substance that can combine with calcium to form kidney stones in susceptible individuals. While a concern primarily for those with a history of kidney stones or kidney disease, a very high intake of collagen could potentially elevate oxalate levels. Staying well-hydrated is key to flushing out excess oxalate and reducing risk.

Potential for drug interactions

While pure collagen is a protein naturally produced by the body and has few known drug interactions, it is essential to consider the potential for other ingredients in supplement formulas to interact with medications. For example, some collagen products are fortified with vitamins like biotin or other herbal extracts that can interfere with certain medications. Individuals taking blood thinners, antibiotics, or anti-inflammatory drugs should consult a healthcare professional before starting supplementation.

Regulatory pitfalls and biased studies

Unlike prescription drugs, the Food and Drug Administration (FDA) does not regulate the safety and efficacy of dietary supplements before they are sold to the public. This means the quality, purity, and even the ingredient content can vary significantly between brands. Furthermore, many studies highlighting the benefits of collagen are funded by supplement companies, raising concerns about potential bias in the research findings. It is important to approach these claims with a critical eye and prioritize third-party tested products.

Weighing the downsides against the benefits

To make an informed decision, it's helpful to compare the potential risks with the claimed benefits.


Downside (Risk)	Key Considerations	Benefit (Claim)	Key Considerations
Digestive Issues	Can cause bloating, gas, nausea, and diarrhea, especially with lower-quality products or high doses.	Improved Skin Health	Studies suggest increased hydration and elasticity and reduced wrinkles for some individuals. Results can vary and take months to appear.
Heavy Metal Contamination	Some products contain contaminants like lead and cadmium due to lax regulation. Requires research into third-party testing and brand transparency.	Joint Pain Relief	Research, particularly on type II collagen, shows promise for reducing joint pain in osteoarthritis patients. Effects can be mild and inconsistent.
Kidney Stone Risk	Hydroxyproline conversion to oxalate poses a risk for susceptible individuals, though moderation is generally safe.	Bone Density Support	Studies in postmenopausal women with low bone density show potential for increasing bone mineral density over time.
Allergic Reactions	Individuals with fish, shellfish, or egg allergies must check the source of the collagen to avoid reactions.	Hair and Nail Health	Some anecdotal reports and smaller studies suggest benefits for hair and nail growth, but stronger clinical evidence is lacking.
High Cost	Some supplements can be expensive, and results are not guaranteed. A balanced diet with adequate protein may be a cheaper alternative.	Muscle Mass	Some studies show potential for increasing muscle mass, especially when combined with resistance training.

Conclusion

While many people take collagen powder to support skin, joint, and bone health, it is important to understand that potential downsides exist. The risks range from common, mild digestive issues to more serious concerns like heavy metal contamination and increased risk of kidney stones for predisposed individuals. The supplement industry's relative lack of regulation means quality and safety are not uniform across all products, and efficacy claims can be biased. To minimize risk, consumers should prioritize third-party tested products and be mindful of their specific health conditions, including allergies and kidney history. Ultimately, a balanced, nutrient-dense diet may provide the necessary building blocks for natural collagen production for many people, and a supplement may not be a necessary or worthwhile investment. Before adding any supplement to your regimen, a consultation with a healthcare professional is always the wisest course of action.

For more information on supplement purity testing, visit the Clean Label Project.

Frequently Asked Questions

Yes, some individuals may experience digestive side effects such as bloating, gas, and an upset stomach, particularly when starting supplementation or taking higher doses. Opting for hydrolyzed collagen peptides from a reputable brand can help minimize this issue.

Some collagen powders have been found to contain heavy metals like lead and cadmium. This risk is due to environmental exposure in the source animals and a lack of strict regulation in the supplement industry. Consumers should seek third-party tested products to ensure purity.

For most healthy individuals, moderate collagen intake is safe for the kidneys. However, those with a history of kidney stones or pre-existing kidney disease should consult a doctor, as collagen's hydroxyproline content can increase oxalate levels, potentially contributing to stone formation.

Yes, allergic reactions are possible, especially if you have allergies to the source material. Collagen is typically derived from beef, marine life, or poultry. Symptoms can include skin rashes, itching, or swelling. Check the source and consult a doctor if you have known allergies.

While pure collagen is unlikely to interact with most drugs, other ingredients in supplement blends can. Always consult a healthcare professional, especially if you take blood thinners, antibiotics, or anti-inflammatory drugs, before adding a new supplement to your routine.

There is no official upper limit for collagen, but high doses (over 15-20 grams per day) are more likely to cause digestive issues like an upset stomach. Recommended daily dosages usually fall between 5 and 15 grams, depending on the targeted health benefit.

The body can produce its own collagen from a balanced diet rich in amino acids (from protein sources like meat, beans, and eggs) and vitamin C. A healthy diet is generally the safest and least expensive option, but supplements offer a concentrated dose if desired.