What effect does Viagra have on women?

No. Viagra and similar drugs act by relaxing the muscles that cause blood vessels to expand or contract, allowing more or less blood flow to the penis. These drugs don't affect just the penis; they affect the entire body, and so these drugs are sometimes prescribed to theraputic use for people who have problems with blood flow. Some heart medications have similar effects, and paramedics treating a heart attack will always ask the patient if he has taken Viagra before they begin administering other drugs.