What should I watch for?
If you notice any changes in your vision while taking this drug, call your doctor or health care professional as soon as possible. Stop using this medicine and call your health care provider right away if you have a loss of sight in one or both eyes.
Contact your doctor or health care professional right away if the erection lasts longer than 4 hours or if it becomes painful. This may be a sign of serious problem and must be treated right away to prevent permanent damage.
If you experience symptoms of nausea, dizziness, chest pain or arm pain upon initiation of sexual activity after taking this medicine, you should refrain from further activity and call your doctor or health care professional as soon as possible.
Do not drink alcohol to excess (examples, 5 glasses of wine or 5 shots of whiskey) when taking this medicine. When taken in excess, alcohol can increase your chances of getting a headache or getting dizzy, increasing your heart rate or lowering your blood pressure.
Using this medicine does not protect you or your partner against HIV infection (the virus that causes AIDS) or other sexually transmitted diseases.
Common and Rare Side Effects
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.
Check with your doctor immediately if any of the following side effects occur:
Arm, back, or jaw pain
chest pain or discomfort
chest tightness or heaviness
difficult or labored breathing
difficulty with swallowing
dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
fast, irregular, pounding, or racing heartbeat or pulse
pain or discomfort in the arms, jaw, back, or neck
pounding in the ears
puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
slow or fast heartbeat
tightness in the chest
unusual tiredness or weakness
Incidence not known
Some 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. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
Feeling of warmth and redness of the face, neck, arms, and occasionally, upper chest
abdominal or stomach pain
acid or sour stomach
body aches or pain
burning feeling in the chest or stomach
burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
changes in color vision
changes in vision
difficulty seeing at night
difficulty with moving
difficulty with swallowing
dryness or soreness of the throat
excessive muscle tone
feeling of constant movement of self or surroundings
general feeling of discomfort or illness
increased redness of the eye
increased sensitivity of the eyes to sunlight
lack or loss of strength
loss of appetite
muscle aches and pains
muscle tension or tightness
pain or burning in the throat
sensation of spinning
sleepiness or unusual drowsiness
sores, ulcers, or white spots on the lips or tongue or inside the mouth
stomach discomfort, upset, or pain
tender, swollen glands in the neck
tenderness in the stomach area
trouble with sleeping
trouble with swallowing
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.