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Sildenafil: 7 things you should know

Medically reviewed by Carmen Pope, BPharm. Last updated on July 25, 2023.

1. How it works

2. Upsides

3. Downsides

If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:

Note: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. View complete list of side effects

4. Bottom Line

Sildenafil is used to treat erectile dysfunction (ED) and to reduce blood pressure in pulmonary arterial hypertension (PAH). It is taken when needed for ED and daily for PAH. A headache, stomach upsets, and flushing are the main side effects, and it should not be taken within 24 hours of a nitrate.

5. Tips

6. Response and effectiveness

7. Interactions

Medicines that interact with sildenafil may either decrease its effect, affect how long it works, increase side effects, or have less of an effect when taken with sildenafil. An interaction between two medications does not always mean that you must stop taking one of the medications; however, sometimes it does. Speak to your doctor about how drug interactions should be managed.

Common medications that may interact with sildenafil include:

Sildenafil is metabolized mainly by CYP3A4 and to some extent by CYP2C9. It also weakly inhibits CYP1A2, 2C(, 2C19, 2D^, 2E1, and 3A4. Any drug that is a substrate of one of these enzymes could potentially interact with sildenafil.

In addition, taking sildenafil with too much alcohol can lead to orthostatic hypotension, which is a drop in blood pressure when you go from a sitting or lying down position to standing. Symptoms include a headache, dizziness, or fainting when standing.

Antacids, such as magnesium hydroxide or aluminum hydroxide may also affect the absorption of sildenafil. Grapefruit juice may also increase the side effects of sildenafil.

Note that this list is not all-inclusive and includes only common medications that may interact with sildenafil. You should refer to the prescribing information for sildenafil for a complete list of interactions.

References

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use sildenafil only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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