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:
More common
Blurred vision
change in color vision
changes in behavior
confusion
diarrhea
hearing loss
nausea
ringing in the ears
stomach cramps or pain
vomiting
Less common
Anxiety
behavior change, similar to drunkenness
black, tarry stools
bloody urine
blurred vision or change in vision
chills
cold sweats
confusion
cool pale skin
cough
difficulty concentrating
drowsiness
excessive hunger
fast heartbeat
fever
headache
hoarseness
loss of consciousness
lower back or side pain
nervousness
nightmares
painful or difficult urination
pinpoint red spots on the skin
restless sleep
seizures
shakiness
slurred speech
sore throat
unusual bleeding or bruising
unusual tiredness or weakness
Rare
Difficulty breathing or swallowing
disturbed color perception
double vision
hives
increased sweating
muscle aches
night blindness
reddening of the skin, especially around ears
ringing or buzzing in the ears
swelling of the eyes, face, inside of the nose, fingers, feet, or lower legs
Incidence not known
Back, leg, or stomach pains
bleeding gums
bleeding under the skin
blindness
blistering, peeling, or loosening of the skin
bloody nose
blue-yellow color blindness
change in mental status
chest pain
cold sweats
confusion
cool, pale skin
cough
dark urine
decreased frequency or amount of urine
decreased vision
depression
diarrhea
difficulty breathing
difficulty in moving
difficulty speaking
dizziness
dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
eye pain
fainting
fast, pounding, or irregular heartbeat or pulse
general body swelling
general feeling of discomfort, illness, or weakness
hoarseness
heavier menstrual periods
hoarseness
increased hunger
increased or decreased urination
increased sensitivity of the skin to sunlight
increased thirst
irregular heartbeat, recurrent
irritation
itching, skin rash
joint pain, stiffness, or swelling
light-colored stools
loss of appetite
muscle cramps, weakness, or stiffness
nervousness
nightmares
nosebleeds
painful or difficult urination
pale color of the skin
pale skin
red skin lesions, often with a purple center
red, irritated eyes
redness or other discoloration of the skin
severe
sunburn
sores, ulcers, or white spots in the mouth or on the lips
tightness in the chest
troubled swallowing
upper right abdominal pain
weakness
weight gain
yellow eyes or skin
Get emergency help immediately if any of the following symptoms of overdose occur:
Symptoms of an overdose
Blindness
blurred vision or change in vision
chest pain
dizziness
double vision
fainting
lightheadedness
rapid or irregular heartbeat
sleepiness
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:
Incidence not known
Feeling of warmth
heartburn
lack or loss of strength
pain or burning in the throat
problems with speech or speaking
restlessness
thoughts or attempts of killing oneself tremors
unsteadiness, trembling, or other problems with muscle control or coordination
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.
 Quinine side effects (more detail)
