Viagra, or Sildenafil, has been available since 1998 and is the simplest to use of the new drugs for erection difficulties. It can be taken without anybody knowing, there are hardly any side-effects, and, when it works, you can depend on it. Erection only occurs when the man is sexually excited.

A starting dose of 25-50mg, later increasing to a maximum of 100mg in a 24 hour period, may cause mild side-effects. These can be facial flushing in about 20 minutes, slight indigestion, coloured haloes around objects and a mild headache. These effects are dose-related and pass off quickly.

If Viagra is taken before an evening meal a better erection response occurs with sexual excitement for up to 18 hours; the greatest effect lasts about 4 hours starting about an hour after taking the tablet.

There are some medical conditions which mean you must not use Viagra.If you are taking other medications such as erythromycin or cimetidine, you should only take half the dose of viagra. This is why it is so important to have it from a doctor.