Drug interaction checker
GLP-1, PDE5 inhibitors, and finasteride combined with your other medications
Select one or more medications to see possible interactions.
This tool reflects published FDA labels, clinical pharmacology references, and our editorial review. It is not a substitute for consultation with a licensed prescriber or pharmacist. Always disclose all medications, supplements, and substances to your healthcare team. Editorial policy.
About this tool
This checker uses published FDA prescribing information, the Lexicomp interaction severity convention, and editorial review by our medical board. It is intentionally focused on the GLP-1, ED, and hair-loss medications we cover. For interactions with medications outside this scope, see the comprehensive interaction databases at Drugs.com or your pharmacist.
What the severity levels mean
- Contraindicated: Do not combine. Life-threatening or therapy-failing combination. Example: PDE5 inhibitors (Viagra, Cialis) with any nitrate including recreational nitrites ("poppers").
- Major: Significant caution required. Often requires dose adjustment, intensive monitoring, or coordination across prescribers. Example: GLP-1 + insulin (hypoglycemia risk).
- Moderate: Clinically meaningful, manage proactively. Example: GLP-1 + oral contraceptives (delayed absorption during titration).
- Minor: Small effect, awareness only. Example: GLP-1 + levothyroxine (minor absorption delay, rarely requires dose change).