Can Taking Collagen Cause Negative Side Effects?

November 27, 2025 •

4 min read

Although collagen is the most abundant protein in the human body, providing structure to our skin, bones, and joints, supplementary forms are not without potential downsides. Knowing if taking collagen can cause negative side effects is crucial for making an informed decision about your health routine.

Quick Summary

Collagen supplements can cause mild digestive issues like bloating, heartburn, or diarrhea, and in rare cases, trigger allergic reactions depending on the source. Individuals with kidney problems or allergies to fish, beef, or chicken should exercise caution. Dosage, supplement quality, and individual health factors are key in managing any potential adverse effects.

Key Points

Digestive Issues: Mild side effects like bloating, gas, heartburn, and upset stomach are the most commonly reported negative effects of taking collagen supplements.
Allergy Potential: Collagen is often sourced from animals (bovine, marine, chicken), and those with corresponding allergies are at risk for reactions.
Kidney Concerns: Individuals with a history of kidney stones or kidney disease should be cautious, as a collagen component can increase oxalate levels.
Lack of Regulation: The supplement industry is not heavily regulated, raising concerns about potential heavy metal contamination in low-quality products.
Limited Research in Special Groups: The effects of collagen on pregnant or breastfeeding women are not well-established, and medical consultation is advised.
Source Matters: The type and source of collagen can influence digestibility, taste, and potential allergens.

Collagen supplements are a popular addition to many health and beauty regimens, prized for their potential benefits to skin, joints, and bones. However, the assumption that more is always better, or that all supplements are universally safe, is misleading. While most users tolerate collagen well, understanding potential adverse reactions is vital for safe supplementation.

Common and Mild Side Effects

For many, any negative experience with collagen is minor and often related to the digestive system. These issues are usually temporary as the body adjusts, and may depend on the dosage and supplement formulation.

Digestive Discomfort

Bloating and gas: The introduction of a new protein source, especially in higher doses, can cause bloating and gas as the gut adjusts.
Heartburn and nausea: Some individuals report feelings of heartburn or mild nausea, though this is relatively rare.
Diarrhea or constipation: These opposing issues can both occur. Diarrhea may be a result of poorly absorbed collagen, while constipation can arise if the protein intake isn't accompanied by sufficient water consumption.
Unpleasant aftertaste: Marine-sourced collagen, in particular, can leave a metallic or fishy aftertaste, which some find difficult to tolerate.

Skin Reactions and Histamine Issues

Though less common, some people may experience skin-related side effects, potentially due to underlying sensitivities or the supplement's ingredients.

Rashes and acne: Mild skin rashes or an increase in acne have been reported in some individuals. This could be a sign of hypersensitivity to a component in the supplement or an impurity.
Histamine intolerance: For those with existing histamine intolerance, the amino acids in collagen can sometimes trigger reactions like headaches, fatigue, or hives, as collagen is naturally high in histamine.

Potential Risks for Specific Groups

Certain pre-existing health conditions or circumstances can increase the risk associated with collagen supplementation. Consulting a doctor before starting any new supplement is always recommended.

Kidney Health Concerns

Kidney stones: Collagen contains an amino acid called hydroxyproline, which is converted to oxalate in the body. While normally harmless, too much oxalate can increase the risk of kidney stone formation, especially for those with a history of them or existing kidney conditions.
Kidney strain: Excessive protein intake from supplements, including collagen, can place an extra burden on the kidneys. Individuals with compromised kidney function should monitor their intake carefully.

Risks during Pregnancy and Breastfeeding

Limited research: The effects of collagen supplements on pregnant or breastfeeding individuals are not well-studied. Due to the lack of sufficient data, it is best to avoid supplementation unless explicitly approved by a healthcare provider.

Drug Interactions

Blood pressure medication: While generally not an issue, some evidence suggests that a high-protein diet may reduce the effectiveness of certain blood pressure medications, like propranolol. Always discuss potential interactions with a doctor.

The Unregulated Supplement Landscape

Because the supplement market is largely unregulated by the FDA, the risk of contamination is a real concern. Choosing a low-quality product can expose you to harmful substances.

Heavy metal contamination: Reports have found some collagen supplements testing positive for heavy metals like arsenic, lead, and cadmium. Seeking brands that are third-party tested by organizations like NSF or USP is the best way to ensure product purity.
Filler ingredients: In addition to contaminants, low-quality supplements may contain unnecessary fillers or additives that can cause their own side effects.

Comparison of Collagen Sources


Source	Collagen Type(s)	Primary Use	Potential Allergy Risk	Other Considerations
Bovine	Type I & III	Skin, bones, joints	Beef allergy	Widely available, often more affordable.
Marine	Type I	Skin (beauty benefits)	Fish or shellfish allergy	Considered more bioavailable, some report an unpleasant aftertaste.
Chicken	Type II	Joint and cartilage health	Chicken allergy	Often used specifically for joint support.
Eggshell	Types I, V, X	Joints, skin, connective tissue	Egg allergy	Often includes additional beneficial components.

How to Minimize Risks

Taking a proactive approach can help you enjoy the potential benefits of collagen while minimizing your exposure to risks.

Start with a lower dose: Begin with a small daily amount to see how your body reacts before increasing to a standard dose.
Choose reputable, third-party tested brands: Look for certifications from trusted organizations like NSF, USP, or ConsumerLab.com to ensure product quality and purity.
Check the source: Read the label carefully to identify the source of the collagen (bovine, marine, etc.), especially if you have known allergies to certain animal products.
Stay hydrated: Ensure you are drinking plenty of water, as this can help aid digestion and prevent potential constipation, especially when consuming higher protein levels.
Listen to your body: If you notice any persistent or concerning symptoms, stop taking the supplement and consult a healthcare professional.

Conclusion

While collagen is generally a safe and well-tolerated supplement, it is not free of potential negative side effects. The most common issues are mild and digestive in nature, but allergic reactions, risks related to pre-existing kidney conditions, and potential contamination in unregulated products pose more serious concerns. By understanding the source of your supplement, choosing a high-quality product, and consulting with a healthcare provider, you can navigate supplementation with a greater awareness of the potential risks and rewards. For those with specific health concerns, or during pregnancy and breastfeeding, professional medical advice is essential before adding any new supplement to your routine.

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Frequently Asked Questions

Yes, some people experience bloating and gas, especially when first starting. This can be due to the introduction of a new protein source or, in some cases, the supplement's molecular size.

Yes, it is possible. Allergic reactions are most often tied to the supplement's animal source (e.g., fish, shellfish, beef). Individuals with known allergies should check product labels carefully.

Individuals with kidney issues or a history of kidney stones should be cautious and consult a doctor before use. A component in collagen can increase oxalate levels, which can contribute to stone formation.

Excessively high doses can lead to digestive discomfort, feelings of fullness, and potentially place stress on the kidneys over time. Sticking to recommended doses is best.

While there are no widespread documented interactions, a high-protein diet might affect certain medications, like some blood pressure drugs. It is always wise to consult a healthcare provider.

Choose supplements from reputable brands that undergo third-party testing for purity. Look for certifications from organizations like NSF International or USP.

Marine collagen can cause issues for people with fish or shellfish allergies and may also have a stronger aftertaste for some. Some marine-sourced products have also been linked to potential hypercalcemia at high doses.