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Viagra

Generic Name: Sildenafil citrate
Product Name: Viagra

Indication of Viagra

Viagra is a medication used to treat men with erectile dysfunction, also known as impotence. Men with erectile dysfunction are unable to get or keep an erection that is hard enough for sexual activity. Viagra helps these men to achieve an erection when they become sexually excited. It does not increase their sex drive or cause them to have an erection if they are not sexually excited.

Viagra is not used to treat women.

Action of Viagra

Viagra is one of a group of medicines called phosphodiesterase-5 (PDE-5) inhibitors. It causes the blood vessels in the penis to relax when a man becomes sexually excited, so that more blood flows into his penis. This is the same process that occurs when a man gets an erection without using Viagra.

Dose advice of Viagra

Dose information

Viagra is only available with a doctor’s prescription. Always take the dose prescribed by the doctor, even if the doctor prescribes a different dose to that recommended on the leaflet. The correct dose varies between men, depending for example on whether they have any health conditions. Do not take more than one dose of Viagra each day.

Taking too much Viagra increases your risk of experiencing side effects, some of which can be very serious. If you take too much Viagra, contact the Poisons Information Centre for advice, even if you do not feel sick.

Viagra usually takes 30–60 minutes to start working. It may take longer if you have just eaten a heavy meal. You should take your Viagra tablet about an hour before you plan to have sexual intercourse. Always swallow the tablet whole with a full glass of water. Do not take Viagra if the expiry date printed on the packet has passed or if the packaging is torn or broken. In this case, the tablets should be returned to the pharmacy for correct disposal.


Storage

Viagra should be stored in its original packaging, out of reach of children, in a dry, cool place. Ideally it should be kept in a locked cabinet at least 1.5 metres off the ground. The medicine should not be left in the bathroom, near a sink, on a windowsill or in a car.


While taking Viagra

Note that Viagra will only work if you are sexually excited. Excessive alcohol consumption may impair your ability to achieve an erection. Do not consume large quantities of alcohol prior to sexual activity.

If you are taking Viagra and you fail to achieve an erection when you become sexually excited, or if you cannot keep an erection for long enough to have satisfactory sex, tell your doctor. They may need to change the dose.

Viagra, particularly when taken in high doses, may cause dizziness and visual problems and affect your ability to drive or operate machinery. Become familiar with your reaction to Viagra before driving. If your vision is affected when you take Viagra (e.g. you see colours differently), do not drive or operate machinery whilst using the drug.

If you experience vision loss, stop taking Viagra and seek medical attention urgently.

If you experience a persistent erection which will not go away (a condition known as priapism) for > 4 hours, seek medical attention. Priapism may cause damage to penile tissues if left untreated.

While you are being treated with Viagra, always tell your doctor, dentist or pharmacist that you are taking Viagra before they prescribe you any other medication.

If you experience an attack of angina (a heart problem characterised by severe chest pains), seek medical attention immediately. Tell your doctor you are using Viagra. Do not use nitrate-containing medications for angina while you are being treated with Viagra.


If you have any queries about the correct way to use Viagra, please ask your doctor.


Contraindications

Viagra should not be used under certain conditions. Tell your doctor if you:

  • Have an allergy to sildenafil citrate (the active ingredient in Viagra) or any of the other ingredients;
  • Use nitrate-containing medicines: Medicines containing glyceryl trinitrate(also called nitroglycerin), and other types of nitrates should not be used at the same time as Viagra. Nitrates are most commonly uses to treat a heart condition called angina which causes chest pain. Viagra increases the blood pressure-lowering effects of nitrate-containing medicines, which include:
    • Tablets including Anginine, Lycinate, Nitrostat, Imdur Durules, Monodur Durules, Sorbidin, Isordil, Corangin, Ismo 20, Imtrate, Duride, Isomonit, Ikorel and sodium nitroprusside;
    • Patches including Nitro-Dur, Transiderm-Nitro, Nitroderm TTS and Minitran;
    • Sprays including Nitrolingual and Glytrin;
    • Injections including glyceryl trinitrate concentrate; and
    • Others: Nitrate-containing medications may also be sold under other names. If you are taking any medications which you think may contain nitrate, check with your doctor before you start taking Viagra;
  • Use amyl nitrate: Amyl nitrate is a recreational drug often called a “popper”. These drugs contain nitrate, which is dangerous when taken at the same time as Viagra;
  • Have a heart or blood vessel problem which means you should not have sex: Severe heart and blood vessel problems can make having sex dangerous, because the physical exertion of sexual intercourse may cause stress on the heart. Tell your doctor if you have a heart problem that may make sex dangerous for you. Your doctor may ask to check your heart health before starting you on Viagra, particularly if it has been a long time since you last had sex.
  • Had a heart attack in the past 6 months;
  • Had a stroke in the last 6 months;
  • Have a severe liver condition;
  • Have low blood pressure if you are not controlling your blood pressure with medication;
  • Have high blood pressure if you are not controlling your blood pressure with medication;
  • Have previously lost sight in one or both eyes due to an eye disorder called non-arteritic anterior ischaemic optic neuropathy.


Precautions

Special care needs to be taken when using Viagra under certain conditions. Tell your doctor if you have:

  • Allergy to any substance, including medicines, food and dyes;
  • A heart problem: Viagra treatment is aimed at helping you to engage in sexual activity, which is a risk factor for life-threatening heart problems such as heart attacks. The doctor will need to check the condition of your heart before prescribing Viagra.
  • A problem with your blood vessels: Viagra may also increase your risk of cardiovascular problems and other dangerous events like stroke because it causes your blood pressure to decrease. The doctor will need to assess the condition of your blood vessels before starting Viagra treatment;
  • Previously experienced sudden vision loss in one or both eyes: You may be at risk of experiencing vision loss again if you take Viagra. If you experience vision loss while taking Viagra, stop using the medicine immediately and seek urgent medical attention;
  • Diabetes, particularly if you experience eye problems such as diabetic retinopathy as a result of your diabetes;
  • A kidney problem;
  • A liver problem;
  • Leukaemia (cancer of the blood cells);
  • Multiple myeloma (cancer of the bone marrow);
  • Sickle cell anaemia (a disease of the blood);
  • A disease or deformity of the penis;
  • A condition that causes you to bleed abnormally, such as haemophilia;
  • Stomach ulcers;
  • Vision problems affecting the way you see colour;
  • Experienced sudden hearing loss in the past;
  • Any other condition which affects your health.

Also tell your doctor if you use other medications, including:

  • Other medications for treating your erectile dysfunction;
  • Other medications that may interfere with the way Viagra works. You may need to take a different dose of Viagra. Tell your doctor if you are taking any medication so that they can check whether or not it will affect the way Viagra works. Medicines known to effect Viagra include:
    • A medicine called cimetidine, used to treat ulcers;
    • Some anti-fungal medications, including ketoconazole and itraconazole;
    • Some antibiotics, including erythromycin and rifampicin;
    • Medicines used to treat HIV infection called protease inhibitors, including ritonavir and saquinavir;
    • Medicines called alpha blockers, which may be used to treat high blood pressure or prostate disorders.


Pregnancy

Viagra is a Pregnancy Category B1 medication. It should not be used to treat women.


Breastfeeding

Viagra should not be used by women.


Children

Viagra should not be used to treat males < 18 years of age.

Schedule of Viagra

Viagra is a Schedule 4 medication.1

Common side effects of Viagra

All medicines have side effects. Most commonly the side effects are minor; however, some can be more serious. Usually the benefits of taking a medication outweigh the associated side effects. Your doctor would have considered these side effects before starting you on Viagra.

If you experience any side effects while taking Viagra, tell your doctor.


Very common side effects

Very common side effects are those that occur in more than 10% of people given Viagra. These include:

  • Headache;
  • Flushing;
  • Indigestion (observed to occur very commonly only at 100 mg doses of Viagra);
  • Abnormal vision (observed to occur very commonly only at 100 mg doses of Viagra).


Common side effects

Common side effects are those that occur in 2–10% of people given Viagra. These include:

  • Indigestion;
  • Blocked nose;
  • Diarrhoea;
  • Rash;
  • Urinary tract infection, which causes a stinging sensation when you urinate;
  • Changes to your vision, including changes to the way you see colours or loss of vision (observed to occur very commonly only at 100 mg doses of Viagra);
  • Dizziness.

Uncommon side effects of Viagra

Side effects that occur in less than 1% of people given Viagra are considered uncommon. People do not necessarily experience any of these side effects, so do not become alarmed by this list. Side effects that occur in less than 2% of patients given Viagra include:

  • Infection;
  • Facial swelling;
  • Sensitivity to light;
  • Shock;
  • Weakness;
  • Pain;
  • Chills;
  • Accidental fall;
  • Abdominal pain;
  • Allergic reaction;
  • Chest pain;
  • Accidental injury;
  • Hypersensitivity reaction, which may cause a skin rash, facial swelling and difficulty breathing. Seek urgent medical attention if you experience these symptoms;
  • Heart function abnormalities, including heart attack, heart failure and irregular heart beat;
  • Migraine;
  • Fainting;
  • Low blood pressure, which may be due to changes in posture;
  • Decreased blood flow to the heart;
  • Abnormal thickening or enlargement of the heart;
  • Widening of the blood vessels;
  • Bloot clot in the brain;
  • Nausea;
  • Vomiting;
  • Inflammation of the digestive system, including the mouth, nose and throat;
  • Difficulty swallowing;
  • Dry mouth;
  • Abnormal liver function test results;
  • Rectal bleeding;
  • Anaemia and other blood test abnormalities;
  • Thirst;
  • Swelling;
  • Gout;
  • Abnormalities in blood glucose control;
  • Abnormalities in blood chemistry;
  • Joint pain and inflammation;
  • Muscle pain;
  • Bone pain;
  • Tendon rupture;
  • Tendon inflammation;
  • Muscle weakness;
  • Nervous system conditions, including shaking and tremor;
  • Nerve disorders and pain;
  • Paralysis;
  • Vertigo;
  • Depression;
  • Insomnia;
  • Sleepiness;
  • Abnormal dreams;
  • Decreased reflexes;
  • Increased sensitivity of the sense organs, but particularly the skin in response to cold, heat or pain;
  • Seizure;
  • Anxiety;
  • Asthma;
  • Difficulty breathing;
  • Inflammation of the respiratory system;
  • Increased coughing;
  • Increased phlegm production;
  • Raised itchy welts;
  • Cold sores;
  • Itching;
  • Sweating;
  • Skin ulcer;
  • Skin disorders;
  • Dilated pupils;
  • Infection of the eye (Conjunctivitis);
  • Eye pain;
  • Ringing sound or pain in the ears;
  • Sudden hearing loss;
  • Bleeding from or in the eyes;
  • Burning sensation in the eyes;
  • Swelling of or increased pressure in the eyes;
  • Bloodshot and/or dry eyes;
  • Temporary vision loss;
  • Cataract;
  • Double vision;
  • Dislocation of the retina;
  • Increased fluid build-up in the macula;
  • Other eye diseases;
  • Prostate disorders;
  • Inflammation of the bladder;
  • Increased need to urinate, including at night;
  • Breast enlargement;
  • Urinary incontinence;
  • Abnormal ejaculation;
  • Build-up of fluids in the genital organs;
  • Inability to achieve orgasm;
  • Priapism (an erection that will not subside);
  • Abnormally long duration of erection;
  • Blood in the urine.


Other side effects are also known to affect men who take Viagra. If you experience any of the listed side effects, or any other symptoms that appear abnormal or unusual, please tell your doctor.

What to do if you take too much Viagra

Taking too much of any drug, including Viagra, is called an overdose. If you take too much Viagra, you are more likely to experience side effects. If you think you or anyone you know has taken too much Viagra, you should immediately telephone your doctor or the Poisons Information Centre. Do this even if there are no signs of discomfort.

References:

  1. Product Information: Viagra Tablets. West Ryde, NSW: Pfizer Australia Pty Ltd; 26 October 2009.
  2. Consumer Medical Information: Viagra Tablets. West Ryde, NSW: Pfizer Australia Pty Ltd; September 2009.

Related documents:

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Diseases/conditions treated by Viagra:

 

For further information talk to your doctor.

Dates

Posted On: 22 July, 2003
Modified On: 25 June, 2012
Reviewed On: 7 November, 2011

 



Created by: myVMC