The most common side effects of the active ingredients (sildenafil, tadalafil, and vardenafil) in Peakʳˣ include headaches, nasal congestion, flushing, dizziness, and upset stomach.
Most side effects are mild, but PDE-5 inhibitors like these have the potential for rare, serious side effects, such as low blood pressure and priapism (a prolonged erection lasting four hours or more). If you experience a prolonged erection, seek emergency medical attention immediately.
Do not take Peakʳˣ more than once in any 24-hour period or within 24 hours of using any other ED medication or PDE-5 inhibitors.