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Sildenafil Australia

Sildenafil Australia

How it works

Viagra works by binding to an enzyme called phosphodiesterase. Viagra binding to the enzyme prevents it from converting the chemical cyclic guanosine monophosphate (abbreviated cGMP) into guanosine triphosphate (GTP).

The effect of a build-up in cGMP is the relaxing of artery walls. This makes the arteries bigger and thus allows more blood to flow into the penis.

However, the drug will not give patients an erection without sexual stimulation. When a man becomes aroused the brain sends a signal to the cells in the penis to release nitric oxide, which turns on the production of cGMP. Without the stimulation to produce nitric oxide, there is no cGMP build-up and no erection.

How to take this medicine

Follow carefully all directions given to you by your doctor. Their instructions may be different to the information in this leaflet.

How much to take

Your doctor will decide the correct dose for you depending on your condition and response.

This can be one 25 mg tablet a day or one 50 mg tablet a day or one 100 mg tablet a day.

Side effects

  • headache
  • dizziness
  • flushing
  • indigestion
  • stuffy nose
  • changes in vision such as blurring, a blue colour to your vision or a greater awareness of light
  • muscle aches, back or limb pain
  • rash
  • diarrhoea or upset stomach
  • a numbness or tingling skin sensation
  • breathlessness or coughing
  • fever or flu like symptoms
  • nose bleeds
  • difficulty sleeping
  • hayfever


The information about this medicine comes from trusted sources.

Therapeutic Goods Administration (TGA)

Pharmaceutical Benefits Scheme (PBS)

  • GuildLink
  • DrugBank

healthdirect medicines information is not intended for use in an emergency. If you are suffering an acute illness, overdose, or emergency condition, call triple zero (000) and ask for an ambulance.

Reasonable care has been taken to provide accurate information at the time of creation. This information is not intended to substitute medical advice, diagnosis or treatment and should not be exclusively relied on to manage or diagnose a medical condition. Please refer to our terms and conditions.

Australian regulatory information

According to the TGA Ingredient Database, sildenafil is available for use as an:

Active ingredient in biologicals, export only and prescription medicines;

Excipient ingredient in biologicals, devices and prescription medicines; and

Equivalent ingredient in prescription medicines.

Sildenafil is listed in 102 registered products on the Australian Register of Therapeutic Goods (ARTG). These include 25 mg, 50 mg and 100 mg tablets.

In the last 20 years there have been 1075 adverse event reports in the Database of Adverse Events Notification (DAEN) - Medicines: 967 cases with a single suspected medicine and 39 cases of death as a reported outcome. Of the cases where sildenafil was suspected, reactions include dyspepsia, dizziness, headache, insomnia, urinary tract infection, diarrhoea, flushing and nausea.