Check with your doctor immediately if any of the following side effects occur while taking VIAGRA:

Less Common:

bladder pain
burning feeling in the chest or stomach
burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
cloudy or bloody urine
dizziness
increased frequency of urination
indigestion
pain on urination
stomach upset
tenderness in the stomach area

Rare:

abnormal vision
anxiety
behavior change similar to drunkenness
bleeding of the eye
blurred vision
bone pain
breast enlargement
chest pain
chills
cold sweats
confusion
convulsions (seizures)
cool and pale skin
deafness or hearing loss
decrease in amount of urine or the frequency of urination
decreased vision
difficulty in concentrating
dizziness or lightheadedness, especially when getting up suddenly from a lying or sitting position
double vision
drowsiness
dry eyes
dry mouth
dryness, redness, scaling, or peeling of the skin
excessive hunger
eye pain
fainting or faintness
fast, irregular, or pounding heartbeat
feeling of something in the eye
fever or chills
headache (severe or continuing)
increase in the size of the pupil
increased sweating
increased thirst
lower back or side pain
migraine headache
nausea (severe or continuing)
nervousness
nightmares
numbness of the hands
painful, swollen joints
prolonged, painful erection of penis
redness, burning, or swelling of the eyes
redness, itching, or tearing of the eyes
restless sleep
seeing shades of colors differently than before
sensitivity to light
shakiness
skin lesions with swelling
skin paleness
skin rash, hives, or itching
skin ulcers
slurred speech
sore throat
sudden weakness
swelling of the face, hands, feet, or lower legs
trouble breathing
twitching of the muscles
unusual feeling of burning or stinging of the skin
unusual tiredness or weakness
vision changes
vision loss, temporary
Incidence not known
Blindness

Some side effects of viagra 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:

More Common:

aches or pains in the muscles
bloody nose
diarrhea
difficult or labored breathing
flushing
headache
pain or tenderness around the eyes and cheekbones
redness of the skin
sneezing
stomach discomfort following meals
stuffy or runny nose
trouble sleeping
unusually warm skin

Rare:

Abdominal or stomach pain
abnormal dreams
anxiety
clumsiness or unsteadiness
cough
diarrhea or stomach cramps (severe or continuing)
difficulty in swallowing
ear pain
increased amount of saliva
increased skin sensitivity
lack of coordination
loss of bladder control
mental depression
nausea
numbness or tingling of the hands, legs, or feet
rectal bleeding
redness or irritation of the tongue
redness, soreness, swelling, or bleeding of the gums
ringing or buzzing in the ears
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
sleepiness
sores in the mouth and on the lips
tense muscles
trembling and shaking
vomiting
waking to urinate at night
worsening of asthma