Diarrhea, gas, upset stomach, or stomach pain may occur in the first few weeks of treatment as your body adjusts to this medication but usually improve with time. If any of these effects persist or worsen, notify your doctor or pharmacist promptly.
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.
Miglitol does not cause low blood sugar (hypoglycemia). However, this effect can occur if you also take other anti-diabetic drugs (e.g., sulfonylureas, insulin) and if you do not consume enough calories (from food, juices, fruit, etc.). The symptoms include chills, cold sweat, blurred vision, dizziness, drowsiness, shaking, rapid heart rate, weakness, headache, fainting, tingling of the hands or feet, or hunger. Do not use table sugar or drink non-diet soda to relieve these symptoms because miglitol delays the breakdown of table sugar. Carry glucose tablets or gel with you to treat low blood sugar. If you are in a situation where you don't have these reliable forms of glucose, eat some honey or drink a glass of orange juice to quickly raise your blood sugar level. Tell your doctor immediately about the reaction. To help prevent hypoglycemia, eat meals on a regular schedule and do not skip meals.
Check with your doctor or pharmacist about what you should do if you miss a meal.
Symptoms of high blood sugar (hyperglycemia) include thirst, increased urination, confusion, drowsiness, flushing, rapid breathing, or fruity breath odor. If these symptoms occur, tell your doctor immediately. Your medication dosage may need to be increased or you may need other drugs.
This medication may rarely cause a serious intestinal condition (pneumatosis cystoides intestinalis). Tell your doctor right away if you develop: persistent diarrhea, constipation, blood/mucus in stool.
A very serious allergic reaction to this drug is unlikely, but seek immediate medical attention if it occurs. Symptoms of a serious allergic reaction may include: rash, itching/swelling (especially of the face/tongue/throat), 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.
In the US -
Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.