PATIENT INFORMATION
METFORMIN HYDROCHLORIDE
TABLETS, USP
Read this information carefully before you start taking this
medicine and each time you refill your prescription. There may be new
information. This information does not take the place of your doctor's advice.
Ask your doctor or pharmacist if you do not understand some of this information
or if you want to know more about this medicine.
What is Metformin?Metformin is used to treat type 2 diabetes. This is also known as
non-insulin-dependent diabetes mellitus. People with type 2 diabetes are not
able to make enough insulin or respond normally to the insulin their bodies
make. When this happens, sugar (glucose) builds up in the blood. This can lead
to serious medical problems including kidney damage, amputations, and blindness.
Diabetes is also closely linked to heart disease. The main goal of treating
diabetes is to lower your blood sugar to a normal level.
High blood sugar can be lowered by diet and exercise, by a number of
medicines taken by mouth, and by insulin shots. Before you take metformin, try
to control your diabetes by exercise and weight loss. While you take your
diabetes medicine, continue to exercise and follow the diet advised for your
diabetes. No matter what your recommended diabetes management plan is, studies
have shown that maintaining good blood sugar control can prevent or delay
complications of diabetes, such as blindness.
Metformin helps control your blood sugar in a number of ways. These include
helping your body respond better to the insulin it makes naturally, decreasing
the amount of sugar your liver makes, and decreasing the amount of sugar your
intestines absorb. Metformin does not cause your body to make more insulin.
Because of this, when taken alone, they rarely cause hypoglycemia (low blood
sugar), and usually do not cause weight gain. However, when they are taken with
a sulfonylurea, hypoglycemia is more likely to occur, as is weight gain.
WARNINGA small number of people who have taken
metformin have developed a serious condition called lactic acidosis. Lactic
acidosis 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 metformin. (See “What are the side effects of
metformin?”)
Who should not take
metformin?Some conditions increase your chance of getting lactic acidosis,
or cause other problems if you take metformin. Most of the conditions listed
below can increase your chance of getting lactic acidosis.
Do not take metformin if you:
- have kidney problems
- have liver problems
- have heart failure that is treated with medicines, such as Lanoxin® (digoxin) or Lasix® (furosemide)
- drink a lot of alcohol. This means you binge drink for short periods or
drink all the time
- are seriously dehydrated (have lost a lot of water from your body)
- are going to have an x-ray procedure with injection of dyes (contrast
agents)
- are going to have surgery
- develop a serious condition, such as heart attack, severe infection, or a
stroke
- are 80 years or older and you have NOT had your kidney function
tested
Tell your doctor if you are pregnant or plan to become pregnant. Metformin
may not be right for you. Talk with your doctor about your choices. You should
also discuss your choices with your doctor if you are nursing a child.
Can metformin hydrochloride tablets,
USP be used in children?Metformin hydrochloride tablets, USP has been shown to
effectively lower glucose levels in children (ages 10 to 16 years) with type 2
diabetes. Metformin hydrochloride tablets, USP have not been studied in children
younger than 10 years old.
Metformin hydrochloride tablets, USP have not been studied in combination
with other oral glucose-control medicines in children. If you have any questions
about the use of metformin hydrochloride tablets, USP in children, talk with
your doctor or healthcare provider.
How should I take metformin
hydrochloride tablets, USP?Your doctor will tell you how much medicine to take and when to
take it. You will probably start out with a low dose of the medicine. Your
doctor may slowly increase your dose until your blood sugar is better
controlled. You should take metformin with meals.
Your doctor may have you take other medicines along with metformin to control
your blood sugar. These medicines may include insulin shots. Taking metformin
hydrochloride tablets, USP with insulin may help you better control your blood
sugar while reducing the insulin dose.
Continue your excercise and diet program and test your blood sugar regularly
while taking metformin.
Your doctor will monitor your diabetes and may perform blood tests on you
from time to time to make sure your kidneys and your liver are functioning
normally. There is no evidence that metformin causes harm to the liver or
kidneys.
Tell your doctor if you
- have an illness that causes severe vomiting, diarrhea or fever, or if you
drink a much lower amount of liquid than normal. These conditions can lead to
severe dehydration (loss of water in your body). You may need to stop taking
metformin for a short time.
- plan to have surgery or an x-ray procedure with injection of dye (contrast
agent). You may need to stop taking metformin hydrochloride tablets for a short
time.
- start to take other medicines or change how you take a medicine. Metformin
can affect how well other drugs work, and some drugs can affect how well
metformin works. Some medicines may cause high blood sugar.
What should I avoid while taking
metformin hydrochloride tablets, USP?Do not drink a lot of alcoholic drinks while taking metformin.
This means you should not binge drink for short periods, and you should not
drink a lot of alcohol on a regular basis. Alcohol can increase the chance of
getting lactic acidosis.
What are the side effects of
metformin?Lactic Acidosis.
In rare cases, metformin can cause a serious
side effect called lactic acidosis. This is caused by a buildup of lactic acid
in your blood. This build-up can cause serious damage. Lactic acidosis
caused by metformin is rare and has occurred mostly in people whose kidneys were
not working normally. Lactic acidosis has been reported in about one in 33,000
patients taking metformin over the course of a year. Although rare, if lactic
acidosis does occur, it can be fatal in up to half the people who develop
it.
It is also important for your liver to be working normally when you take
metformin. Your liver helps remove lactic acid from your blood.
Make sure you tell your doctor before you use metformin if you have kidney or
liver problems. You should also stop using metformin and call
your doctor right away if you have signs of lactic acidosis. Lactic acidosis is
a medical emergency that must be treated in a hospital.
Signs of lactic acidosis are:
- feeling very weak, tired, or uncomfortable
- unusual muscle pain
- trouble breathing
- unusual or unexpected stomach discomfort
- feeling cold
- feeling dizzy or lightheaded
- suddenly developing a slow or irregular heartbeat
If your medical condition suddenly changes, stop taking metformin and call
your doctor right away. This may be a sign of lactic acidosis or another serious
side effect.
Other Side Effects.Common side effects of metformin include diarrhea, nausea, and
upset stomach. These side effects generally go away after you take the medicine
for a while. Taking your medicine with meals can help reduce these side effects.
Tell your doctor if the side effects bother you a lot, last for more than a few
weeks, come back after they've gone away, or start later in therapy. You may
need a lower dose or need to stop taking the medicine for a short period or for
good.
About 3 out of every 100 people who take metformin have an unpleasant
metallic taste when they start taking the medicine. It lasts for a short
time.
Metformin rarely cause hypoglycemia (low blood sugar) by themselves. However,
hypoglycemia can happen if you do not eat enough, if you drink alcohol, or if
you take other medicines to lower blood sugar.