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Sildenafil

Drug Class: Commonly Known As: Category:
Phosphodiesterase Type 5 Inhibitor Viagra

Sildenafil - What is it for

​Sildenafil is used to treat erectile dysfunction, a condition where you are unable to get or keep an erection firm enough to have sexual intercourse. It works by relaxing the blood vessels in your penis, allowing blood to flow into your penis when you get sexually excited. This medicine will only help you to get an erection if you are sexually stimulated. Therefore it is taken on an as-needed basis.

This medication may also be used for other conditions. Check with your healthcare professional if you are unsure why you are given this medicine

Sildenafil - Side Effects, Precautions, and Contraindications

What side effects can Sildenafil cause?

  • ​Facial flushing where the skin on your face feels hot
  • Headache
  • Visual disturbances (including blurring of vision, blue tinge in vision)
  • Indigestion or stomach pain
  • Nosebleed

Priapism (an erection that will not go away) - If you have an erection that lasts more than 4 hours, get medical help right away. If it is not treated right away, priapism can permanently damage your penis.

Sudden vision loss in one or both eyes - Sudden vision loss in one or both eyes can be a sign of a serious eye problem called non-arteritic anterior ischemic optic neuropathy (NAION).

Sudden hearing decrease or hearing loss - Some people may also have ringing in their ears (tinnitus) or dizziness.

The symptoms of a drug allergy include one or more of the following:

  • Swollen face/eyes/lips/tongue
  • Difficulty in breathing
  • Itchy skin rashes over your whole body

If you experience any of these symptoms, you should stop your medication and see your healthcare professional immediately.

Before taking Sildenafil, what precautions must I follow?

​Inform your healthcare professional if:

  • You are allergic to this medication or any of the other ingredients of this medication
  • You are taking medicines called Nitrates (such as sublingual nitroglycerin (also known as Glycerin Trinitrate or GTN), Isosorbide Mononitrate or Isosorbide Dinitrate), as the combination may lead to a dangerous fall in your blood pressure. Nitrates must be withheld at least 24 hours after the last dose of Sildenafil or Vardenafil, and 48 hours after the last dose of Tadalafil.
    Tell your doctor if you are taking any of these medicines which are often given for relief of angina (chest pain).  If you are not certain, ask your healthcare professional.
  • You are taking medicines called Alpha-1 Blockers (such as Tamsulosin, Terazosin, Prazosin, Alfuzosin), as the combination may further lower your blood pressure. In order to reduce the chances of these symptoms occurring, you should be on a regular daily dose of your Alpha-1 blockers before you start drugs for erectile dysfunction.
  • You recently had a stroke or a heart attack, low blood pressure or uncontrolled high blood pressure
  • You have severe heart, liver or kidney  problem
  • You have certain rare inherited eye diseases (such as retinitis pigmentosa)
  • You have a stomach ulcer or bleeding problem
  • You have sickle cell anaemia (an abnormality of red blood cells)
  • You have a deformity of your penis

What food or medicine must I avoid when I take Sildenafil?

Avoid taking grapefruit, or grapefruit juice as they may interact with your medication and increase the risk of side-effects.

Drinking alcohol can temporarily weaken your ability to get an erection and may increase the blood pressure lowering effects of the medication, which can be dangerous. To get the maximum benefit from your medication, it is advisable not to drink excessive amounts of alcohol before taking this medication.

Inform your healthcare professional if you are taking or intend to take any other medication, supplements, traditional medications or herbal remedies.

This includes certain medications such as:

  • Antibiotics
  • Anti-fungal medications
  • Medications used to treat human immunodeficiency virus (HIV) infection

Sildenafil - Dosage and How to Use

How should Sildenafil be used?

    • It usually starts to work within 1 hour and effective up to 4 hours before sexual activity.
    • This medication should be taken before food, on an empty stomach. You may find that this medicine takes longer to start working if you take it with a high-fat meal (such as cheeseburger and french fries)

What should I do if I miss a dose?

  • Do not take more than once a day or the dose prescribed for you.

What should I do if I overdose?

Sildenafil - Handling and Storage

How should I handle Sildenafil safely?

How should I store Sildenafil?

Keep away from children;#Keep in a cool, dry place, away from direct sunlight;#

How should I dispose of Sildenafil safely?

​Pack this medication into a black trash bag and seal it tightly before throwing into the rubbish chute or bin.

Sildenafil - Additional Information

  • Updated on Monday, September 30, 2019
  • Article contributed by PSS National Medication Information Workgroup

    The information provided is not intended as medical advice. Terms of use. Information provided by SingHealth

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