What is Sildenafil? Uses, warnings & side effects

How to take Sildenafil

• Your doctor will tell you how much sildenafil to take and how often it can be taken. Do not use more than directed.

• Sildenafil doses can be taken with or without food.

• Please read the Patient Information sheet before taking sildenafil.

For erectile dysfunction:

• Take the prescribed dose about one hour before anticipated sexual activity. 

• The dose could still work if it’s taken one-half hour to four hours before sexual activity.

• Sexual stimulation is needed for sildenafil to work.

• Do not take more than one dose in a 24-hour period.

• Store sildenafil tablets at room temperature.

For pulmonary arterial hypertension: 

• Take or administer the prescribed dose three times a day, four to six hours apart.

How to take sildenafil oral suspension:

• Sildenafil oral suspension is prescribed for pulmonary hypertension.

• Please read and follow the Instructions for Use.

• Do not use sildenafil oral suspension if it’s still in powder form.

• Shake the bottle for at least 10 seconds before measuring a dose.

• Use the oral syringe provided with the medicine to measure doses.

• Do not mix the dose with other liquids or flavorings.

• The person getting the medicine should be sitting or standing upright.

• Place the syringe in the mouth against the cheek and squirt the dose into the cheek.

• Wash the syringe with water and allow it to dry after each use.

• Store sildenafil oral suspension in the refrigerator. Do not freeze.

• Throw away any unused medicine 60 days after receiving it.

• Liqrev oral suspension can be kept for 90 days before it must be thrown away.

What to do if you miss a dose of Sildenafil

• For erectile dysfunction:

  • If a dose is missed, take it when remembered but wait at least 30 minutes before attempting sexual activity.

  • Do not take two or more doses in any 24-hour period. 

• For pulmonary hypertension:

  • Take a missed dose as soon as it’s remembered. 

  • If it’s almost time for the next dose, skip the missed dose and take the next dose as scheduled.

  • Never take extra sildenafil to compensate for a missed dose.

Sildenafil contraindications - Who shouldn't take Sildenafil?

• This medicine is not right for everyone. 

• Do not use it if you have had an allergic reaction to sildenafil.

Sildenafil warnings

• Tell any doctor or other healthcare provider who treats you that you are taking sildenafil. 

• The doctor may need to perform regular check-ups and tests to check the effectiveness and side effects of this treatment. Keep all appointments.

• Tell your doctor if you are pregnant, breastfeeding, or have:

  • Kidney disease

  • Liver disease

  • Diabetes

  • Bleeding problems

  • Blood problems such as sickle cell anemia 

  • Bleeding problems or ulcers

  • Obstruction of the small veins in the lungs (pulmonary veno-occlusive disease) 

  • Eye or vision problems

  • Deformed penis shape

• If sildenafil is prescribed for erectile dysfunction, the prescriber will need to know if you have:

  • Chest pain during sex

  • Heart disease

  • Heart rhythm problems

  • Low blood pressure or uncontrolled high blood pressure

  • Any previous heart attack or stroke

  • Any heart surgery in the last six months

  • Pulmonary hypertension

  • Multiple myeloma

  • Any history of prolonged erections (longer than four hours)

• Make sure the doctor knows if you smoke or not.

• Sildenafil can cause serious problems, particularly at high doses:

  • Heart problems

  • Low blood pressure

  • Prolonged or painful erections

  • Sudden loss of vision in one or both eyes

  • Hearing problems including hearing loss, ringing in the ears, and dizziness

• Sexual activity strains the heart. If sildenafil is being used for ED, do not continue having sex if you experience symptoms of heart problems such as chest pain or nausea.

• Sildenafil for ED does not protect you or your partner from sexually transmitted diseases.

Sildenafil interactions & what to avoid when taking Sildenafil

• Because of potentially hazardous drug interactions, sildenafil can never be safely used with:

  • Other PDE-5 inhibitors such as vardenafil or tadalafil

  • The pulmonary hypertension treatment Adempas (riociguat)

  • Nitrates such as nitroglycerin

  • Drugs that enhance sexual performance called “poppers” such as amyl nitrite

• To avoid other drug interactions, make sure the prescriber knows about all prescription drugs, over-the-counter medications, and supplements you use, particularly:

  • Alpha blockers, medicines commonly used to treat enlarged prostate or high blood pressure

  • Other types of blood pressure drugs

  • Other treatments or supplements for erectile dysfunction

  • HIV/AIDS medications called protease inhibitors

  • Azole antifungal drugs such as ketoconazole and itraconazole

  • The antibiotics clarithromycin and erythromycin

  • Amlodipine, bosentan, cimetidine, rifampin

Find more detailed information about sildenafil interactions to avoid here.