Coffee Consumption Linked to Kidney Risk in Slow Metabolizers and Interacts with Common Medications

A long‑term study of adults with stage‑1 hypertension found that drinking more than three cups of coffee per day was associated with almost three times the risk of early kidney‑damage markers such as albuminuria, but only in people who genetically metabolise caffeine slowly (CYP1A2 variant). The research highlights that the risk is not universal and depends on individual caffeine metabolism.

Separate health guidance notes that caffeine can interfere with several widely used medicines. It may amplify stimulant effects when combined with decongestants like pseudoephedrine, reduce absorption of levothyroxine for hypothyroidism and bisphosphonates for osteoporosis, and alter the efficacy of certain antidepressants and antipsychotics that share metabolic pathways with caffeine. Users are advised to separate coffee intake from these drugs to avoid reduced effectiveness or heightened side effects.