Health Facts PlusDrug Information: Sildenafil (Systemic)
belongs to a group of medicines that delay the enzymes called phosphodiesterases from working too quickly. The penis is one of the areas where these enzymes work. Sildenafil is used to treat men who have erectile dysfunction (also called sexual impotence).By controlling the enzyme phosphodiesterase, sildenafil helps to maintain an erection that is produced when the penis is stroked. Without physical action to the penis, such as that occurring during sexual intercourse, sildenafil will not work to cause an erection.Sildenafil is also used to treat the symptoms of pulmonary arterial hypertension. This is the high blood pressure that occurs in the main artery that carries blood from the right side of the heart (the ventricle) to the lungs. When the smaller blood vessels in the lungs become more resistant to blood flow, the right ventricle must work harder to pump enough blood through the lungs. Sildenafil helps by increasing the supply of blood to the lungs and reducing the workload of the heart.This medicine is available only with your doctor''s prescription, in the following dosage form(s): Oral
Before Using This MedicineReturn to top
In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For sildenafil, the following should be considered:
Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to sildenafil. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.
Pregnancy—Sildenafil is not indicated for use in women. Sildenafil has not been studied in pregnant women. However, sildenafil has not been shown to cause birth defects or other problems in animal studies.
Breast-feeding—It is not known whether sildenafil passes into breast milk. Sildenafil is not indicated for use in women for erectile dysfunction. Mothers who are taking this medicine for pulmonary arterial hypertension and who wish to breast-feed should discuss this with their doctor.
Older adults—Elderly people are especially sensitive to the effects of sildenafil, which may increase their chance of having side effects. Patients 65 years of age and older who are taking this medicine for erectile dysfunction are started on a low dose, 25 mg, of sildenafil. Patients who are taking this medicine for pulmonary arterial hypertension may also need to be started at a lower dose. The dose may be increased by a doctor as needed and tolerated.
Other medicines—Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking sildenafil, it is especially important that your health care professional know if you are taking any of the following: Alpha-blockers (medicine for high blood pressure—Sildenafil when taken together with an alpha-blocker medicine may cause very low blood pressure. Sildenafil doses above 25 mg should not be taken within 4 hours of taking an alpha-blocker medicine.
Bosentan (e.g., Tracleer)—May increase amounts of bosentan in the body
Erythromycin (e.g., E.E.S. or Ery-Tab)
Saquinavir (e.g., Fortovase or Invirase)—These medicines may increase the unwanted effects of sildenafil, unless lower starting doses of sildenafil are used
Erectile dysfunction medicines—These medicines should not be used at the same time as sildenafil because the safety of using these medicines in combination has not been proven.
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
Other medical problems—The presence of other medical problems may affect the use of sildenafil. Make sure you tell your doctor if you have any other medical problems, especially: Age greater than 50 years or
Hyperlipidemia (excess of lipids in the blood) or
Low cup to disc ratio (“crowded disc”) or
Smoking—These conditions may increase risk for a serious eye problem called NAION.
Heart attack, history of (within the last 6 months) or
Stroke, history of (within the last 6 months)—Chance of problems occurring may be increased
Abnormal penis, including curved penis and birth defects of the penis—Chance of problems occurring may be increased
Retinitis pigmentosa—Chance of problems occurring may be increased. It is not known if the medicine is safe for use in these patients
Conditions causing thickened blood or slower blood flow, including leukemia; multiple myeloma (tumors of the bone marrow); or polycythemia, sickle cell disease, and thrombocythemia (blood problems) or
Priapism (history of)—Although sildenafil does not cause priapism (erection lasting longer than 6 hours), patients with these conditions have an increased risk of priapism and it could occur while using sildenafil
Heart or blood disease—Sexual activity increases the heart rate and blood flow and can increase the chance of problems occurring for some patients who use any type of medicine, including sildenafil, that increases sexual ability
Liver problems (severe)—Chance of problems occurring may be increased. Lower starting doses may be used and doses increased as needed and as tolerated
NAION (serious eye condition) in one or both eyes, previously—May increase your chance of getting NAION again.
Pulmonary veno-occlusive disease (high blood pressure in the blood vessels of the lungs)—May make heart problems worse in patients with this serious condition
Proper Use of This MedicineReturn to top
Special patient directions come with sildenafil. Read the directions carefully before using the medicine.This medicine usually begins to work within 30 minutes after taking it for erectile dysfunction. It continues to work for up to 4 hours, although its action is usually less after 2 hours.Dosing—The dose of sildenafil will be different for different patients. Follow your doctor''s orders or the directions on the label. The following information includes only the average doses of sildenafil. If your dose is different, do not change it unless your doctor tells you to do so. For oral dosage form (tablets): For treatment of erectile dysfunction: Adults up to 65 years of age—50 mg as a single dose no more than once a day, 1 hour before sexual intercourse. Alternatively, the medicine may be taken 30 minutes to 4 hours before sexual intercourse. If needed, your doctor may increase your daily dose to 100 mg or decrease your daily dose to 25 mg.
Adults 65 years of age and older—25 mg as a single dose no more than once a day, 1 hour before sexual intercourse. Alternatively, the medicine may be taken 30 minutes to 4 hours before sexual intercourse. If needed, your doctor may increase your daily dose.
If you are taking protease inhibitors, such as for the treatment of HIV, your doctor may recommend a 25 mg dose and may limit you to a maximum single dose of 25 mg of Viagra in a 48 hour period
For treatment of pulmonary arterial hypertension: Adults—20 mg three times per day. Each dose should be taken about 4 to 6 hours apart and can be taken with or without food.
Children—Use and dose must be determined by your doctor.
Storage—To store this medicine: Keep out of the reach of children.
Store away from heat and direct light.
Do not store in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.
Keep the medicine from freezing. Do not refrigerate.
Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.
Precautions While Using This MedicineReturn to top
Sildenafil has not been studied with other medicines used for treatment of erectile dysfunction. Presently, using them together is not recommended .It is important that you tell all of your healthcare providers that you take sildenafil. If you need emergency medical care for a heart problem, it is important that your healthcare provider knows when you last took sildenafil.Use sildenafil exactly as directed by your doctor. Do not use more of it and do not use it more often than your doctor ordered. If too much is used, the chance of side effects is increased.If you experience a prolonged or painful erection for 4 hours or more, contact your doctor immediately. This condition may require prompt medical treatment to prevent tissue damage of the penis and possible permanent impotence.This medicine does not protect you against sexually transmitted diseases. Use protective measures and ask your doctor if you have any questions about this.It is important to tell your doctor about any heart problems you may have now or may have had in the past. This medicine can cause serious side effects in patients with heart problems.If you experience sudden loss of vision in one or both eyes, stop using sildenafil and contact your doctor immediately.
Side Effects of This MedicineReturn to top
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Abnormal vision, including blurred vision, seeing shades of colors differently than before, or sensitivity to light;
burning, crawling, itching, numbness, prickling, “pins and needles”, or tingling feelings;
burning feeling in chest or stomach;
decreased vision or other changes in vision;
prolonged, painful, or inappropriate erection of penis;
redness, burning, or swelling of the eye;
Note: The following rare side effects have not been completely established as being caused by sildenafil
Blood sugar problems (more likely with patients with diabetes mellitus), such as anxiety, behavior change similar to drunkenness, blurred vision, cold sweats, confusion, cool and pale skin, difficulty in concentrating, drowsiness, excessive hunger, fast heartbeat, headache, nausea, nervousness, nightmares, restless sleep, shakiness, slurred speech, and unusual tiredness or weakness;
decrease in amount of urine or in frequency of urination;
dizziness or lightheadedness, especially when getting up from a lying or sitting position;
dryness, redness, scaling, or peeling of the skin;
feeling of something in the eye;
groups of skin lesions with swelling;
redness, itching, or tearing of eyes;
shortness of breath or troubled breathing;
sore throat and fever or chills;
swelling of face, hands, feet, or lower legs;
unusual feeling of burning or stinging of skin
Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome:
pain or tenderness around eyes and cheekbones;
Note: The following rare side effects have not been completely established as being caused by sildenafil
diarrhea or stomach cramps (severe or continuing);
numbness or tingling of hands, legs, or feet;
redness or irritation of the tongue;
redness, soreness, swelling, or bleeding of gums;
sensation of motion, usually whirling, either of one''s self or of one''s surroundings;
sexual problems in men (continuing), including failure to experience a sexual orgasm;
sores in mouth and on lips;
Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.
Impotence therapy agent (systemic)Antihypertensive (pulmonary)
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