Gemfibrozil belongs to the class of medications known as fibrates. It is used to treat high cholesterol. It works by blocking the production of certain types of cholesterol, especially the type known as triglycerides.

Gemfibrozil is used in combination with a healthy diet and exercise to lower cholesterol and triglyceride levels in the blood. Reduction of cholesterol levels has been shown to reduce the risks associated with heart disease, such as heart attack.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

The recommended adult dose of gemfibrozil is 600 mg twice daily, 30 minutes before the morning and evening meals. The maximum daily recommended dose of gemfibrozil is 1,500 mg.

Many things can affect the dose of a medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important to take this medication exactly as prescribed by your doctor. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature and keep it out of the reach of children.

Do not take gemfibrozil if you:

• are allergic to gemfibrozil or any ingredients of the medication
• are allergic to fenofibrate or any other medications in the class of "fibrates" (e.g., clofibrate, bezafibrate)
• are breast-feeding
• are pregnant
• are taking a medication for diabetes called repaglinide
• are taking a medication for high cholesterol called cerivastatin
• have a disorder known as type 1 hyperlipoproteinemia
• have liver disease, kidney disease, or gallbladder disease

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• diarrhea
• heartburn
• nausea
• skin rash
• stomach pain, gas, or heartburn
• vomiting

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• signs of kidney problems (e.g., decreased urination, nausea, vomiting, swelling of the feet and ankles)
• signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
• unusual tiredness or weakness

Check with your doctor immediately if any of the following side effects occur:

• symptoms of muscle breakdown (e.g., muscle pain, unexplained muscle weakness, general feeling of being unwell, fever)
• stomach pain (severe) with nausea and vomiting

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Blood counts: Rarely, this medication will decrease the number of neutrophils (a type of white blood cell that helps fight infection), red blood cells (which carry oxygen), and platelets (which help your blood to clot). Your doctor will do blood tests to monitor this. If you notice any signs of infection (e.g., fever, chills, or sore throat), fatigue, or unusual bleeding or bruising, contact your doctor as soon as possible.

Gallbladder disease: This medication may increase the risk for gallstones. If you have a history of gallbladder disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Liver function: Liver disease or reduced liver function may cause this medication to build up in the body, causing side effects. If you have liver problems, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. Your doctor may want to test your liver function regularly with blood tests while you are taking this medication.

If you experience symptoms of liver problems such as fatigue, feeling unwell, loss of appetite, nausea, yellowing of the skin or whites of the eyes, dark urine, pale stools, abdominal pain or swelling, and itchy skin, contact your doctor immediately.

Muscle effects: When combined with medications in the HMG-CoA reductase inhibitors class (commonly referred to as "statins"), there is an increased risk of muscle breakdown. If you are taking gemfibrozil and one of these medications, discuss with your doctor how this medication may affect your medical condition, and whether any special monitoring is needed.

If you experience symptoms of muscle breakdown, such as generalized weakness, muscle pain, or a general feeling of being unwell, with or without fever, contact your doctor immediately.

Pregnancy: Strict birth control methods must be used by women who may become pregnant while taking this medication. If you become pregnant despite using birth control, stop taking gemfibrozil and contact your doctor. Women who are planning to become pregnant should stop taking gemfibrozil several months before conception.

Breast-feeding: It is not known if gemfibrozil passes into breast milk. If you are breast-feeding and are taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of this medication have not been established for children.

There may be an interaction between gemfibrozil and any of the following:

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.