4 known interactions • 1 major • 3 moderate • 0 minor
Always disclose all medications to your healthcare providers — prescription medicines, OTC medications, vitamins, and herbal supplements. This list may not include every possible interaction. Use our Medicine Interaction Checker to screen your complete medication list.
Potentially life-threatening or causing permanent damage. Avoid combination.
May worsen condition or require dose adjustment. Monitor closely.
Usually limited clinical effect. Manage with routine monitoring.
Monoamine oxidase inhibitors (MAOIs)
Risk of hypertensive crisis when phentermine combines with MAOI therapy.
Management: Contraindicated. Wait 14 days after stopping an MAOI before starting Qsymia.
Oral contraceptives
Topiramate increases estrogen clearance, potentially reducing contraceptive efficacy.
Management: Use non-hormonal backup contraception or higher-dose pill at the prescriber's direction.
CNS depressants and alcohol
Additive sedation and cognitive impairment.
Management: Avoid alcohol and limit other sedating drugs.
Carbonic anhydrase inhibitors (e.g., zonisamide, acetazolamide)
Increased risk of metabolic acidosis and kidney stones.
Management: Avoid combination when possible.
Always ask your pharmacist about potential interactions with food, alcohol, and supplements specific to Qsymia. Some medicines have significant interactions with grapefruit juice, high-fat meals, dairy products, or vitamin K-rich foods.