Questions to Ask Your Clinician or Pharmacist About Collagen or Creatine

How to use this list

This page gives you questions, not answers. Whether collagen or creatine is right for you depends on your health, medicines and plans, and only a clinician or pharmacist who knows you can weigh that. The FDA advises people to talk to their doctor, pharmacist or other healthcare professional before deciding to purchase or use a dietary supplement. [1] The US National Institutes of Health adds that supplements may interact with medicines or carry risks with certain medical problems or surgery. [2]

If you have trouble breathing, swelling of the lips, mouth, throat or tongue, do not use this list. Call 911 in the US. [3]

Before the visit: what to bring

• The product itself or a photo of the whole label, including the Supplement Facts panel and the ingredient list. For label reading, see A Collagen and Creatine Label Checklist.
• A list of every medicine, vitamin and supplement you take, with the amounts. NIH says to tell your providers about all supplements you are taking. [2]
• Any study or claim that made you consider the product. Our amount tables show what studies used, not what is right for you: collagen and creatine.

Questions for everyone

1. Is there a reason I need this, or is it a marketing claim I read? What would you look at first (diet, protein intake, a test) before adding a supplement?
2. Could this product interact with my medicines or with other supplements? NIH warns that some products interact with medicines. [2] See Medication Interactions.
3. Does anything in my health history make this a poor idea?
4. If I try it, what would you want me to watch for, and who do I contact if something feels wrong? Supplement problems can also be reported through the US Safety Reporting Portal. [2]
5. Is the product itself reliable? What can a label and a testing program tell me, and what can't they? See Quality Testing and Certifications. NIH says the FDA can act on unsafe supplements only after they are on the market. [2]

Questions about collagen

1. I have an allergy to fish, shellfish, egg or beef. Which collagen sources should I avoid? A case report describes anaphylaxis in a child with fish allergy after fish collagen gummies. [4] See Collagen Allergy.
2. I have had kidney stones. Does that matter? Collagen contains hydroxyproline. The only study we found on its link to oxalate and stones was in rats, which is not evidence for people. [5] See Collagen, Hydroxyproline, Oxalate and Kidney Stone Questions.
3. Does this product's mix of added ingredients (vitamins, herbs, sweeteners) matter for my conditions or medicines? See Collagen and Medicines, Kidney or Liver Conditions.
4. For my goal (skin, joints, bone, muscle), what are the better-studied options and what are the limits of collagen research? See Collagen for Skin, Joints and Bone.

Questions about creatine

1. I have kidney disease, I am on dialysis, or I take medicines that affect the kidneys. Should I avoid creatine? A 2026 review says concerns persist about creatine and kidney safety, especially when function is already reduced. [6] Some experts suggest people with existing kidney disease consult a physician first. [7] Please do not stop or change a prescribed medicine without your clinician's guidance. [8]
2. Creatine can raise a kidney blood test. Will my creatinine and eGFR be misread? A meta-analysis of 26 trials found raised serum creatinine with creatine, but no difference in a different filtration measurement, which the authors read as altered creatinine handling rather than kidney injury. [9] Ask whether another way of checking kidney function is appropriate, and tell the clinician before blood work. See Creatinine, eGFR and Cystatin C. MedlinePlus notes that meat and some supplements can affect creatinine results. [8] See Creatine, Kidney Questions and Creatinine Testing.
3. I am under 18, or I am asking for my teen. Some labels warn against use under 18; a sports-nutrition society calls that a legal precaution. [7] Ask a pediatrician. See Creatine for Teens and Young Athletes.
4. I am pregnant, trying to conceive, or breastfeeding. The International Society of Sports Nutrition (ISSN) describes pregnancy research mainly in animals. [7] Proper evidence not found in the sources we read for human safety amounts. See Creatine in Pregnancy and Breastfeeding.
5. I am an athlete who gets drug tested. A review found about 9 to 15% of supplements tested in studies were contaminated, most often pre-workout, weight-loss and muscle-building products. [10] Ask a pharmacist or your anti-doping body about product checks.

If surgery or a procedure is coming

NIH says some supplements may increase bleeding risk or affect your response to anesthesia, and to talk to your providers as far ahead of an operation as possible. [2] Ask your surgeon and anesthesia team whether to list collagen or creatine, and when. See Supplements Before Surgery.

Questions for a pharmacist specifically

• Can you check this label against my full medicine list?
• Is this the form and strength the label says? (A lab study of 149 creatine samples found 32 adulterated, so quality is a fair question. [11])
• If I get side effects, how do I report them?