warum kein kaffee vor blutabnahme — when to see a doctor?

Coffee before a blood draw can alter several lab values. Caffeine stimulates the sympathetic nervous system, leading to elevated cortisol, adrenaline, and blood glucose levels. Triglycerides and cholesterol may also temporarily rise. For reliable fasting blood tests (e.g., glucose, lipid panel), it is recommended to avoid coffee for 8–12 hours and drink only water. Some tests like complete blood count or thyroid markers are less affected, but to be safe, coffee should generally be avoided before blood draws. When to see a doctor? If you experience symptoms like dizziness, nausea, or circulatory problems after the blood draw, or if results are abnormal (e.g., elevated liver enzymes, anemia). Also, if you regularly drink coffee and suddenly have to abstain, withdrawal symptoms like headaches may occur – discuss this with your doctor. In general, if you are unsure about preparation or interpretation of results, consult a healthcare professional.