sildenafil) belongs to a class of medications, known as phosphodiesterase inhibitors, which are indicated for the treatment of erectile dysfunction in men. Other phosphodiesterase inhibitors include Levitra (vardenafil) and Cialis (tadalafil). These medications are not necessarily different types of Viagra, but treatment alternatives. Cheapest Viagra, commonly referred to as the “little blue pill” was the first erectile dysfunction medication to be approved by the U.S. Food and Drug Administration (FDA).
The usual recommended dose of Viagra is 50 mg administered as needed approximately one hour prior to sexual activity. However, according to the prescribing information, Viagra may be taken anywhere within a range from 30 minutes to four hours prior to sexual activity. The dose of Viagra may be increased to 100 mg or decreased to 25 mg based on therapeutic response and tolerability.
Levitra can decrease blood flow to the optic nerve of the eye, causing sudden vision loss. This has occurred in a small number of people taking Viagra or other drugs similar to vardenafil. Most of these people also had certain pre-existing eye problems or risk factors for blood vessel disorders (such as heart disease, diabetes, high blood pressure, high cholesterol, coronary artery disease, smoking, or being over 50 years old). It is not clear whether vardenafil is the actual cause of vision loss.
Cialis, Cheapest Levitra, and Viagra are all PDE-5 inhibitors. They work by blocking an enzyme called phosphodiesterase type 5 and by boosting a naturally occurring chemical called nitric oxide. This action encourages the muscles in your penis to relax. Relaxed muscles allow blood to flow freely so that when you’re aroused, you can get an erection — and maintain it long enough to have sex.
Levitra and Viagra stay in your bloodstream for about four to six hours, while Cialis remains in your bloodstream for 17 to 18 hours or longer. The length of time a medication stays in your system may be important if you are taking other medications or have prolonged side effects.
Patients with cardiovascular disease could have additional side effects from Viagra, especially in combination with sexual activity. Other common side effects of Viagra include warmth or redness in your face, neck, or chest; stuffy nose; headache; upset stomach; and back pain. More serious, but less frequent side effects include prolonged erection lasting more than 4 hours, vision changes, and loss of hearing. If these occur, you should contact your health care provider.
The maximum recommended dose is 100 mg with a maximum recommended frequency of administration of once daily. Viagra begins to exert its therapeutic effect within one hour with the duration of effects lasting for up to four hours. Erections do not last for four hours, however, a man has the ability to have an erection for up to four hours.