How much time does Viagra take to start working? How does Viagra keep working?
For the strongest effect, take Viagra® about an hour before having intercourse. You can take Viagra® any time between 30 minutes and 4 hours before having sex. Viagra® does not cause an erection by itself. Instead, there must be sexual stimulation to cause an erection. Normally, it starts to work about 10 to 40 minutes after using a dose between 25 and 100 mg. Viagra's effects can last up to four hours, but it will lessen its effect after about two hours. If an erection lasts longer than four hours, be sure to call a doctor. Always take a prescribed medication as directed by a physician for the most effective and safest treatment.
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