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Drug Information Page

Viagra (sildenafil)

Classification: Viagra (sildenafil) belongs to a group of medicines that delay the enzymes called phosphodiesterase from working too quickly.

Form: 25mg, 50mg, and 100mg tablets

Usual Dosage: 

  • 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.
  • In patients taking Protease Inhibitors, FDA recommended dose is 25mg every other day.

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

Side effects to report to your doctor

Common

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

Less Common

  • abnormal vision including 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

Rare

  • bleeding of the eye
  • convulsions (seizures)
  • decreased vision or other changes in vision
  • double vision
  • prolonged, painful, or inappropriate erection of penis
  • redness, burning, or swelling of the eye
  • vision loss
  • anxiety

Drug Interactions and Incompatibility

  • Protease Inhibitors (Crixivan, Invirase, Norvir, Viracept, 
    Fortovase, Agenerase, Lopinavir): Increases the amount of Viagra in your blood and prolongs the action of Viagra. Men on Protease Inhibitors should start with a dose of 25mg and at most use 50mg.
  • Cimetidine (e.g., Tagamet)
  • Erythromycin (e.g., E.E.S. or Ery-Tab)
  • Itraconazole (e.g., Sporanox)
  • Ketaconazole (e.g., Nizoral)
  • Mibefradil (e.g., Posicor):These medicines may increase the unwanted effects of sildenafil, unless lower starting doses of sildenafil are used
  • Nitrates, such as nitroglycerin (e.g., Nitrostat or Transderm-Nitro):Sildenafil increases the lowering of blood pressure by nitrates too much and their use together is not recommended

For more information on Viagra click here.

 
 
 

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