Metronidazole Side Effects
What should I watch for?
Tell your doctor or health care professional if your symptoms do not improve or if they get worse.
You may get drowsy or dizzy. Do not drive, use machinery, or do anything that needs mental alertness until you know how this medicine affects you. Do not stand or sit up quickly, especially if you are an older patient. This reduces the risk of dizzy or fainting spells.
Ask your doctor or health care professional if you should avoid alcohol. Many nonprescription cough and cold products contain alcohol. Metronidazole can cause an unpleasant reaction when taken with alcohol. The reaction includes flushing, headache, nausea, vomiting, sweating, and increased thirst. The reaction can last from 30 minutes to several hours.
If you are being treated for a sexually transmitted disease, avoid sexual contact until you have finished your treatment. Your sexual partner may also need treatment.
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:
burning, numbness, tingling, or painful sensations in the hands or feet
changes in speech patterns
lack of coordination
seeing or hearing things that are not there
shakiness and unsteady walk
stiff neck or back
unsteadiness, trembling, or other problems with muscle control or coordination
unusual tiredness or weakness
weakness in the arms, hands, legs, or feet
Black, tarry stools
blood in the urine
body aches or pain
clumsiness or unsteadiness
difficulty with breathing
feeling of pelvic pressure
frequent or painful urination
loss of voice
pinpoint red spots on the skin
stomach and back pain (severe)
unusual bleeding or bruising
vaginal irritation, discharge, or dryness not present before taking the medicine
loss of appetite
painful or difficult urination
pains in the stomach, side, or abdomen, possibly radiating to the back
sores, ulcers, or white spots on the lips or in the mouth
yellow eyes or skin
Incidence not known
Blistering, peeling, or loosening of the skin
bloody or cloudy urine
burning while urinating
continuing stomach pain
feeling of warmth
increased volume of pale, dilute urine
joint or muscle pain
loss of bladder control
red skin lesions, often with a purple center
red, irritated eyes
redness of the face, neck, arms, and occasionally, upper chest
redness of the skin
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:
Dizziness or lightheadedness
feeling of constant movement of self or surroundings
sensation of spinning
Change in taste sensation
pain or tenderness around the eyes and cheekbones
tender, swollen glands in the neck
trouble with swallowing
unpleasant or sharp metallic taste
Incidence not known
Decreased interest in sexual intercourse
inability to have or keep an erection
loss in sexual ability, desire, drive, or performance
painful sexual intercourse
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.