See also Warning section.
Nausea, stomach upset, diarrhea, or a metallic taste in the mouth may occur
at first as your body adjusts to the medication. If any of these effects persist
or worsen, tell your doctor or pharmacist promptly. If stomach symptoms return
later (after you are on the same dose for several days or weeks), tell your
doctor immediately. Stomach symptoms that occur after the first days of your
treatment may be a sign of lactic acidosis.
Remember that your doctor has prescribed this medication because he or she has
judged that the benefit to you is greater than the risk of side effects. Many
people using this medication do not have serious side effects.
This medication does not usually cause low blood sugar (hypoglycemia). However,
low blood sugar may occur, especially if you take other medications for diabetes,
drink large amounts of alcohol, do unusually heavy exercise, or do not consume
enough calories from food. Symptoms include cold sweat, blurred vision, dizziness,
drowsiness, shaking, fast heartbeat, headache, fainting, tingling of the hands/feet,
and hunger. It is a good habit to carry glucose tablets or gel to treat low
blood sugar. If you don't have these reliable forms of glucose, rapidly raise
your blood sugar by eating a quick source of sugar such as table sugar, honey,
or candy, or drink fruit juice or non-diet soda. Tell your doctor about the
reaction immediately. To help prevent low blood sugar, eat meals on a regular
schedule, and do not skip meals. Check with your doctor or pharmacist to find
out what you should do if you miss a meal.
Symptoms of high blood sugar (hyperglycemia) include thirst, increased urination,
confusion, drowsiness, flushing, rapid breathing, and fruity breath odor. If
these symptoms occur, tell your doctor immediately. Your dosage may need to
be increased.
A very serious allergic reaction to this drug is rare. However, seek immediate
medical attention if you notice any symptoms of a serious allergic reaction,
including: rash, itching, swelling, severe dizziness, trouble breathing.
This is not a complete list of possible side effects. If you notice other effects
not listed above, contact your doctor or pharmacist.