HealthyCanada.com

Prescription needed: Yes

Metformin is used alone or in combination with other medications to treat type-2 diabetes and to decrease the amount of sugar (glucose) in your blood when it cannot be controlled by diet and/or exercise. It works by making the body more sensitive to insulin and by decreasing the amount of sugar (glucose) being made by the liver.

You should not use this drug if you are allergic to it. This drug should not be used and will not work if you have type-1 diabetes. Tell your doctor if you have or have ever had:

• ketoacidosis or lactic acidosis
• problems with your liver or kidney
• heart failure
• severe lung disease (e.g. emphysema)
• a condition called polycystic ovary disease (PCOD) also known as polycystic ovarian syndrome (PCOS)
• problems with stomach cramps diarrhea or pain

Acute problems such as severe burns dehydration vomiting diarrhea high fever severe infection severe heart failure symptoms or severe breathing problems can make your body more sensitive to metformin and increase your chances for the side effect of lactic acidosis.

As well certain medical tests that involve the use of contrast agents (a dye-like substance used to "highlight" an organ) or x-rays may decrease the amount of urine that you produce which in turn could lead to too much metformin in your body. Your doctor may want you to stop taking metformin for at least 48 hours or until he knows for certain that you have normal kidney function.

The most common side effects are

• not feeling hungry
• diarrhea stomach cramps
• metallic taste in your mouth
• passing of gas

These side effects may be lessened with lower doses and may decrease with time. Talk to your doctor or pharmacist about the best way to take this medicine.

Other less common side effects include:

• lactic acidosis - this is an extremely rare side effect and is only a concern when other risk factors are present; talk to your pharmacist or doctor
• low levels of vitamin B 12 in the blood - if occurs usually with long-term therapy and may not cause symptoms of anemia

This is not a complete list of side effects. If you are concerned about these or other unusual symptoms while taking this medication ask your doctor and/or pharmacist for more information and advice.

What if I am taking other drugs?

Always provide your doctor with a list of all other drugs you are taking (including over-the-counter medications and herbal/natural products) as they may interact and may change the safety or effectiveness of either drug. Tell your doctor specifically if you are taking any of these drugs as he/she may need to make changes or check you more closely:

• prednisone dexamethasone cortisone high dose hydrochlorothiazide (>25mg) albuterol pseudoephedrine olanzapine risperidone niacin - these drugs may increase your blood sugar and decrease how well metformin can work

• other diabetes medications (glyburide or other sulfonylureas insulin rosiglitazone pioglitazone repaglinide nateglinide acarbose)
• fenugreek licorice bitter melon eucalyptus ginseng and some other herbal/natural products - these and other natural products have varying effects on blood sugar

• atenolol metoprolol propanolol and other beta-blockers - may decrease your ability to feel the symptoms of low blood sugar

• cimetidine

This is not a complete list of drug interactions. Ask your doctor or pharmacist to review your list of medications.

Monitoring: Regularly check your blood sugar as discussed with your nurse pharmacist or doctor.

Side effect management:

To decrease the chances of having problems with stomach pain and diarrhea it is best to take this medication with food. As well you can slowly increase your dose over a few days to a week to make sure that you can tolerate it.

• Example: If you are given a prescription for Metformin to take 1 - 500mg tablet twice a day you could take 1 -500mg tablet once a day for 3 days and then increase it to twice a day.

If you start to have stomach pain or diarrhea it may be because the dose is too high. If it is mild and you can tolerate it this should go away with time. If you can't stand it talk to your doctor or pharmacist. He/she will likely suggest that you cut your dose in half and increase it to the desired dose more slowly.

Onset of effect: Metformin should start working within a couple days but you may not see its full effect for a couple of weeks. If metformin appears to stop working or doesn't seem to control your blood glucose levels as well as it once did talk to your doctor or other healthcare provider as he or she may need to make some changes.

Children: Not usually prescribed.

Seniors: There is an increased risk of adverse side effects. Reduced dose may be necessary.

Pregnant women: Not usually prescribed. Instead your doctor may substitute insulin as it will provide tighter control.

Women who are nursing: Safety not established. Talk to your doctor.

People who drive or operate machinery: Should not do so until they know the impact this drug has on them personally. This drug may cause low blood sugar when used with other medications for diabetes.

Overdose: Too much metformin can cause a buildup of lactic acid in the body which will make you feel ill. Symptoms include diarrhea fast and shallow breathing severe muscle pain or cramping unusual sleepiness and unusual tiredness or weakness and possibly vomiting. If you experience these symptoms check your blood sugar and get immediate emergency medical help.

If you experience any unusual reactions or if you seriously exceed the recommended dosage call your doctor or 911.

Stopping the drug: Always talk to your doctor before you stop taking this drug. If you stop taking this medicine you may not be able to control your blood sugar levels.

If you miss a dose: Take it as soon as you remember. If next scheduled dose is within two hours take the missed dose and skip the next.

Storage conditions: Closed container; cool dry location away from excess moisture (not in the bathroom); always out of reach of children.

Alcohol: You should not drink a lot of alcohol when taking this medication. Not only can it increase or decrease your blood sugar levels but drinking a lot of alcohol can increase your body's ability to make lactic acid and thus increases your risk for the rare side effect (lactic acidosis) of metformin.

Dietary precautions: Follow your doctor's recommendations. In order to keep your blood glucose levels in control you need to balance your medicine with the right amount of food and exercise.