Key facts
- An erection lasting more than 3 to 4 hours: call 999 or go to A&E.
- Chest pain that feels tight or squeezing: call 999.
- Swelling of the lips, mouth or throat, or trouble breathing: call 999.
- Sudden problems with your sight or hearing: get urgent medical help.
This page lists warning signs, not a full list of side effects. If you're unsure, call NHS 111. In an emergency, call 999.
Call 999 or go to A&E
- An erection that lasts more than 3 to 4 hours (priapism). It can permanently damage the penis without quick treatment.
- Chest pain that feels tight or like squeezing, especially if it spreads to your arms, neck or jaw, or comes with shortness of breath or sweating.
- A serious allergic reaction, such as swelling of the lips, mouth, throat or tongue, or difficulty breathing.
- A seizure.
Get urgent medical help
- Sudden changes to your sight, such as loss of vision in one or both eyes.
- Sudden changes to your hearing.
- Heart palpitations.
For side effects that aren't urgent, see common side effects or contact your prescriber.