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 you have an erection that lasts longer than 4 hours or if it becomes painful. This may be a sign of a 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:
pounding in the ears
slow or fast heartbeat
Arm, back, or jaw pain
bloating or swelling of the face, arms, hands, lower legs, or feet
bloody or cloudy urine
chest pain or discomfort
chest tightness or heaviness
difficult or labored breathing
difficult, burning, or painful urination
fast, irregular, pounding, or racing heartbeat or pulse
frequent urge to urinate
lower back or side pain
pain in the groin or genitals
pain, redness, or swelling in the arm or leg
rapid weight gain
sharp back pain just below the ribs
tightness in the chest
tingling of the hands or feet
unusual tiredness or weakness
unusual weight gain or loss
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
redness of the face, neck, arms, and occasionally, upper chest
stuffy or runny nose
Acid or sour stomach
body aches or pain
change in color vision
cough producing mucus
difficulty having a bowel movement (stool)
difficulty with moving
loss of appetite
loss of voice
muscle pain or stiffness
pain or tenderness around the eyes and cheekbones
burning feeling in the chest or stomach
cool, pale skin
feeling of constant movement of self or surroundings
muscle aching or cramping
sensation of spinning
sleepiness or unusual drowsiness
tenderness in the stomach area
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.