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
Chills
cough
fever
hoarseness
lower back or side pain
painful or difficult urination
Rare
Fever with or without chills
itching, skin rash
nausea
severe stomach cramps and pain
stomach tenderness
unusual bleeding or bruising
vomiting
watery and severe diarrhea, which may also be bloody
yellow eyes or skin
Incidence not known
Anxiety
black, tarry stools
blistering, peeling, or loosening of the skin
blurred vision
chest pain or discomfort
clay-colored stools
confusion about identity, place, and time
cool, pale skin
dark urine
depression
difficulty with swallowing
dizziness
fainting
fast, slow, pounding, or irregular heartbeat or pulse
feeling of unreality
feeling that others are watching you or controlling your behavior
feeling that others can hear your thoughts
feeling, seeing, or hearing things that are not there
hives
increased hunger
joint or muscle pain
light-colored stools
loss of appetite
nightmares
puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
recurrent fainting
red skin lesions, often with a purple center
red, irritated eyes
redness, swelling, or soreness of the tongue
seizures
sense of detachment from self or body
severe mood or mental changes
shakiness
skin eruptions
slurred speech
sore throat
sores, ulcers, or white spots in the mouth or on the lips
stomach pain
swollen glands
tightness in the chest
unpleasant breath odor
unusual behavior
unusual tiredness or weakness
vomiting of blood
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
Belching
bloated or full feeling
change in sensation of taste
excess air or gas in the stomach or bowels
headache
heartburn
indigestion
mild diarrhea
passing gas
Incidence not known
Change in sense of smell
continuing ringing or buzzing or other unexplained noise in the ears
feeling of constant movement of self or surroundings
hearing loss
lightheadedness
loss of taste
mood or mental changes
sensation of spinning
shakiness in the legs, arms, hands, or feet
sore mouth or tongue
swelling or inflammation of the mouth
tongue discoloration
tooth discoloration
trouble sleeping
weight loss
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.
 Biaxin side effects (more detail)
