When to Stop Taking Supplements for Labs

Preparing for your lab appointment thoughtfully ensures you get the most accurate and actionable results. Medications and supplements can affect various biomarkers, so it’s important to know how to approach them before testing.

Note: This guidance is general and may not apply to everyone. Always check with your healthcare provider before making changes to your medication or supplement routine.

Prescription medications

Do not discontinue prescription medications without speaking with your doctor.
If you have questions about a specific medication, ask your clinician whether to take it as usual on the day of your lab appointment.

Supplements

Some members choose to avoid taking vitamins, dietary, and nutritional supplements 48 to 72 hours before their appointment.
Biotin (Vitamin B7) in particular is stopped by many members 72 hours prior to testing, as it can interfere with several hormone and metabolic biomarkers.

Examples: how supplements can affect results

Below are examples of how common supplements may impact different test categories.

❤️ Cardiovascular biomarkers

Fish oil and omega-3s can lower triglycerides, which may affect lipid results.
Niacin (Vitamin B3) may lower LDL and raise HDL.
CoQ10 may influence cholesterol levels.

💧 Kidney function tests

Creatine can raise creatinine.
High-dose Vitamin C may affect creatinine and other kidney markers.
Protein supplements can raise BUN (Blood Urea Nitrogen).

🥼 Liver function tests

Herbal supplements (such as milk thistle, kava, and green tea extract) may alter liver enzymes (ALT, AST, GGT).
Vitamin A and high-dose iron supplements can impact liver enzyme readings.

⚡ Metabolic markers

Biotin can interfere with some glucose and insulin biomarkers.
Vitamin D supplements may influence calcium and phosphate levels.

🩸 Blood and inflammatory markers

Turmeric and fish oil may lower hsCRP due to anti-inflammatory effects.
Iron supplements can raise ferritin and iron saturation.

🧠 Hormonal biomarkers

Biotin can interfere with tests for thyroid hormones, cortisol, and sex hormones.
DHEA, testosterone boosters, or estrogen supplements can directly alter hormone levels.
Adaptogens (such as ashwagandha and rhodiola) may influence cortisol and adrenal hormone measurements.

🥦 Nutrient biomarkers

Zinc and magnesium supplements can elevate measured nutrient levels.
B vitamins (especially B12) may temporarily raise serum B12 and affect homocysteine.