What medications can interact with vitamin C supplements?

Vitamin C in high doses appears to interfere with the blood-thinning effects of anticoagulants such as warfarin by lowering prothrombin time (PT).

Vitamin C may affect blood sugar levels. Caution is advised when using medications that may also affect blood sugar. Patients taking insulin or drugs for diabetes by mouth should be monitored closely by a qualified healthcare professional, including a pharmacist. Medication adjustments may be necessary.

Vitamin C may affect blood pressure. Caution is advised in patients taking agents that affect blood pressure.

Vitamin C may also interact with acetaminophen, acidifying agents, antacids, antibiotics, anticancer drugs, aspirin, barbiturates, cholesterol-lowering agents, diuretics, estrogens, fluphenazine, HIV medications, indinavir, kidney-damaging agents, levodopa, nicardipine, nicotine-containing products (such as cigarettes, cigars, chewing tobacco, or nicotine patches), progesterones, proton pump inhibitors (PPIs), and salicylates.

You should read product labels, and discuss all therapies with a qualified healthcare provider. Natural Standard information does not constitute medical advice, diagnosis, or treatment.