Metformin Hydrochloride, Oral

What are other names for this medicine?

Type of medicine: antihyperglycemic; antidiabetic

Generic and brand names: metformin hydrochloride, oral; Fortamet; Glumetza; Glucophage; Glucophage XR; Riomet

What is this medicine used for?

This medicine is taken by mouth to treat type 2 diabetes when diet and exercise have not controlled blood sugar levels.

This medicine may be used alone or along with other medicines to treat diabetes.

It may be used to treat other conditions as determined by your healthcare provider.

What should my healthcare provider know before I take this medicine?

Tell your healthcare provider if you have ever had:

• an allergic reaction to any medicine
• anemia
• edema (fluid retention)
• heart failure or if you have ever had a heart attack or stroke
• kidney or liver problems
• thyroid, pituitary, or adrenal gland problems

Also tell your provider if you:

• are going to have an X-ray procedure such as a CT scan with the injection of dyes
• are scheduled to have surgery

Tell your provider if you have an illness that results in severe vomiting, diarrhea, or fever, or if you have not been drinking much liquid lately.

Females of childbearing age: Tell your healthcare provider if you are pregnant or plan to become pregnant. Talk to your healthcare provider about whether you will need to use insulin to control your blood sugar during pregnancy. Do not breast-feed while you are taking this medicine without your healthcare provider's approval.

How do I take it?

Check the label on the medicine for directions about your specific dose. Take this medicine every day exactly as your healthcare provider prescribes. Take it with a meal. Follow carefully the diet and exercise plan your healthcare provider gives you. Diet and exercise affect your dosage.

This medicine comes in several forms. Do not break, crush, or chew extended-release tablets. Swallow them whole. If you are not sure if you have the extended-release tablets, ask your pharmacist.

What if I miss a dose?

If you miss a dose, take it as soon as you remember unless it is almost time for the next scheduled dose. In that case, skip the missed dose and take the next one as directed. Do not take double doses. If you are not sure of what to do if you miss a dose, or if you miss more than one dose, contact your healthcare provider.

What if I overdose?

If you or anyone else has intentionally taken too much of this medicine, call 911 or go to the emergency room right away. If you pass out, have seizures, weakness or confusion, or have trouble breathing, call 911. If you think that you or anyone else may have taken too much of this medicine, call the poison control center. Do this even if there are no signs of discomfort or poisoning. The poison control center number is 800-222-1222.

Symptoms of an acute overdose may include: hunger, headache, confusion, irritability, drowsiness, weakness, dizziness, tremors, sweating, fast heartbeat, seizures, fainting, coma, increasing drowsiness, chills, muscle pain, shortness of breath, stomach pain, lightheadedness.

What should I watch out for?

You will need to have blood tests regularly to see if the medicine is working and to check for any signs of side effects that show up only on blood tests. You may be able to do your own testing for blood sugar levels on a small machine at home, but your healthcare provider will do other tests. People with diabetes should also have regular eye exams.

Lactic acidosis is a rare but serious complication that can occur with use of this medicine. This condition is caused by a buildup of lactic acid in the blood. This happens more often in people with kidney problems. Most people with kidney problems should not take this medicine. Stop taking this medicine and contact your healthcare provider right away if you develop unexplained symptoms such as:

• feeling weak or tired
• unusual muscle pain
• having trouble breathing
• feeling cold
• feeling dizzy or lightheaded
• suddenly developing a slow or irregular heartbeat

Low blood sugar (hypoglycemia) can occur if you miss or delay meals, drink too much alcohol, take too much medicine, or exercise more than usual. Symptoms of low blood sugar include confusion, shaking, weakness, strong hunger, cold sweats, headache, nausea, vision problems, and feeling faint. Treat the condition quickly by eating or drinking something with sugar in it such as candy, juice, or nondiet soda. Taking glucose tablets or gels (available in drug stores) is another quick way to treat hypoglycemia. Be sure to talk about this with your healthcare provider.

If you need emergency care, surgery, lab tests, X-rays, or dental work, tell the healthcare provider or dentist you are taking this medicine.

What are the possible side effects?

Along with its needed effects, your medicine may cause some unwanted side effects. Some side effects may be very serious. Some side effects may go away as your body adjusts to the medicine. Tell your healthcare provider if you have any side effects that continue or get worse.

Serious (report these to your healthcare provider right away): Muscle pain; trouble breathing; severe abdominal pain; extreme thirst; irregular heartbeat; severe dizziness; increasing drowsiness; feeling very ill generally; loss of appetite.

Other: Nausea, vomiting, diarrhea, bloating, headache, chest infection, metallic taste in the mouth.

What products might interact with this medicine?

When you take this medicine with other medicines, it can change the way this or any of the other medicines work. Nonprescription medicines, vitamins, natural remedies, and certain foods may also interact. Using these products together might cause harmful side effects. Talk to your healthcare provider if you are taking:

• alcohol
• antiarrhythmic drugs such as procainamide (Pronestyl, Procanbid), amiodarone (Cordarone, Pacerone), quinidine, and dofetilide (Tikosyn)
• antibiotics such as levofloxacin (Levaquin), ciprofloxacin (Cipro), ofloxacin (Floxin), cephalexin (Keflex), trimethoprim (Proloprim, Bactrim, Septra), rifampin (Rifadin, Rimactane), rifabutin (Mycobutin), and vancomycin (Vancocin)
• antiseizure medicines such as carbamazepine (Tegretol), phenytoin (Dilantin), and valproic acid (Depakote, Depakene)
• beta blockers such as atenolol (Tenormin), carvedilol (Coreg), carteolol, labetalol (Trandate, Normodyne), metoprolol (Lopressor, Toprol XL), pindolol, propranolol (Inderal), sotalol (Betapace), and timolol
• birth control pills and hormones such as estradiol (Estrace, Estratab), conjugated estrogens (Premarin), norethindrone (Aygestin, Micronor), and norgestrel (Ovrette)
• calcium channel blockers such as amlodipine (Norvasc), bepridil (Vascor), diltiazem (Cardizem, Dilacor), felodipine (Plendil), nicardipine (Cardene), nifedipine (Procardia, Adalat), verapamil (Calan, Covera, Isoptin), and mibefradil (Posicor)
• corticosteroids such as cortisone (Cortone), dexamethasone, hydrocortisone (Cortef, Hydrocortone), methylprednisolone (Medrol), prednisolone (Delta-Cortef, Prelone), prednisone (Meticorten), and triamcinolone (Aristocort, Kenacort)
• digoxin (Lanoxin)
• diuretics (water pills) such as furosemide (Lasix), hydrochlorothiazide (Microzide), amiloride (Midamor, Moduretic), and triamterene (Dyrenium, Dyazide)
• gemfibrozil (Lopid)
• heartburn medicines such as cimetidine (Tagamet) and ranitidine (Zantac)
• insulin
• isoniazid
• MAO inhibitors such as phenelzine (Nardil), tranylcypromine (Parnate), and isocarboxazid (Marplan) (Do not take this medicine and an MAO inhibitor within 14 days of each other.)
• morphine
• nicotinic acid
• phenothiazines such as chlorpromazine (Thorazine), fluphenazine (Prolixin, Permitil), perphenazine, prochlorperazine (Compazine), promazine (Sparine), thioridazine, and trifluoperazine (Stelazine)
• psyllium
• quinine
• thyroid medicines such as levothyroxine (Levothroid, Levoxyl, Synthroid, Unithroid), liothyronine (Cytomel, Triostat), liotrix (Thyrolar), and thyroid (Armour Thyroid, Thyroid Extract, Thyroid USP)

Do not drink large amounts of alcohol while you are taking this medicine. Talk to your healthcare provider about this.

Keep a list of all your medicines with you. List all the prescription medicines, nonprescription medicines, supplements, natural remedies, and vitamins that you take. Be sure that you tell all healthcare providers who treat you about all the products you are taking.

How should I store this medicine?

Store this medicine at room temperature. Keep the container tightly closed. Protect it from heat, high humidity, and bright light.

This advisory includes selected information only and may not include all side effects of this medicine or interactions with other medicines. Ask your healthcare provider or pharmacist for more information or if you have any questions.

Ask your pharmacist for the best way to dispose of outdated medicine or medicine you have not used. Do not throw medicine in the trash.

Keep all medicines out of the reach of children.

Do not share medicines with other people.