Acquaint yourself with possible side effects before taking Viagra.
The first time you take Viagra in particular, you should watch for signs of unwanted side effects. Some men experience headaches, ringing in the ears, hearing loss, or changes in vision. In some men, an irregular heartbeat is a side effect. If you are at risk for a heart attack, it’s imperative that you talk with your doctor about what you should do if you experience certain side effects, because serious side effects, though very rare, aren’t unheard-of.
Also, whether or not you experience headaches or other side effects mentioned above, seek immediate medical help if you have an erection that lasts longer than four hours. If this problem (known medically as priapism) is not treated, you could experience permanent damage. Don’t try to treat it yourself: this is a situation that warrants a trip to the emergency department.