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:
Less common
Arm, back, or jaw pain
blurred vision
chest pain or discomfort
chest tightness or heaviness
chills
cold sweats
confusion
dizziness
fainting
faintness or lightheadedness when getting up suddenly from a lying or sitting position
fast or irregular heartbeat
headache
hearing loss
nervousness
pain or discomfort in the arms, jaw, back, or neck
pounding in the ears
shortness of breath
slow or fast heartbeat
sweating
unusual tiredness or weakness
vomiting
Rare
Painful or prolonged erection of the penis
Incidence not known
Abdominal or stomach pain
blindness
blistering, peeling, or loosening of the skin
cracks in the skin
decrease or change in vision
difficulty with speaking
double vision
fast, irregular, pounding, or racing heartbeat or pulse
headache, severe and throbbing
hives or welts
inability to move the arms, legs, or facial muscles
inability to speak
joint or muscle pain
loss of heat from the body
numbness or tingling of the face, hands, or feet
red irritated eyes
red skin lesions, often with a purple center
red, swollen skin
redness of the skin
redness or soreness of the eyes
skin rash
slow speech
sores, ulcers, or white spots in the mouth or on the lips
sudden cardiac death
swelling of the feet or lower legs
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:
Less common
Bloody nose
body aches or pain
burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
burning, dry, or itching eyes
burning feeling in the chest or stomach
congestion
difficulty with moving
difficulty with swallowing
dryness or soreness of the throat
excessive eye discharge
feeling of constant movement of self or surroundings
feeling of warmth, redness of the face, neck, arms and occasionally, upper chest
hoarseness
increased erection
lack or loss of strength
loose stools
muscle aching or cramping
muscle stiffness
neck pain
pain in the arms or legs
pain or burning in the throat
redness, pain, swelling of the eye, eyelid, or inner lining of the eyelid
reduced sensitivity to touch
sensation of spinning
sleepiness or unusual drowsiness
spontaneous penile erection
stomach upset
swelling of the eyelids
swelling or puffiness of the eyes or face
swollen joints
tearing
tender, swollen glands in the neck
tenderness in the stomach area
trouble with sleeping
unable to sleep
upper abdominal or stomach pain
voice changes
watering of the eyes
Rare
Changes in color vision
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.
