Viagra and Viagra Side Effects

Viagra (sildenafil) belongs to a group of medicines that delay the enzymes called phosphodiesterase from working too quickly. By delaying the action of phosphodiesterase, blood remains in the penis longer, maintaining an erection for a longer period of time.

• 25mg tablets
• 50mg tablets
• 100mg tablets

• For adults up to 65 years of age, Viagra 50mg is prescribed to be taken once a day, 30 minutes to 4 hours before intercourse. In situations where 50mg isn't effective, your doctor can prescribe 100mg to be taken once daily 30 minutes to 4 hours before intercourse.

• For men older than 65 years of age, Viagra 25mg is prescribed to be taken 30 minutes to 4 hours before intercourse. In some circumstances, men older then 65 may have their doses increased.

• Can be taken with or without food.
• Take 30 minutes to 4 hours before intercourse.
• Always start with the lowest effective dose.

Special Warning! - If you experience any sudden change in vision or loss of vision stop taking Viagra and contact your doctor immediately.

Common

• flushing
• headache
• nasal congestion
• stomach discomfort following meals

Less Common

• blurred vision, seeing shades of colors differently than before, or sensitivity to light
• bladder pain
• cloudy or bloody urine
• dizziness
• increased frequency of urination
• pain on urination
• diarrhea

If you experience an erection that lasts more than 4 hours seek medical attention.

• Protease Inhibitors (Reyataz, Crixivan, Invirase, Norvir, Viracept,Fortovase, Agenerase, Lopinavir) increase the amount of Viagra in your blood and prolongs the action of Viagra. Men on Protease Inhibitors should start with a dose of 25mg with a maximum of 50mg.

• Nitrates, such as nitroglycerin (e.g., Nitrostat or Transderm-Nitro) - Sildenafil further lowers the blood pressure along with nitrates which may result in an abnormally low blood pressure. Use of Viagra with nitrates should be avoided.

For more information on Viagra try About.com's Drug Finder.