Lamivudine and zidovudine belong to a class of medications called nucleoside reverse transcriptase inhibitors (NRTIs). Reverse transcriptase is a part of the human immunodeficiency virus (HIV) required to infect cells and to make more viruses. HIV is the virus responsible for acquired immune deficiency syndrome (AIDS).

Lamivudine and zidovudine are used in combination to treat HIV infection by preventing reverse transcriptase from working properly.

This medication does not cure AIDS and does not prevent it from being spread to others. It is used in combination with other anti-HIV medications to slow further growth or reproduction of HIV. It also seems to slow down the destruction of the immune system. This may help to delay the development of problems such as infections related to AIDS or HIV disease.

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. As well, some forms of this medication may not be used 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 dose for adults and adolescents 12 years of age and older, weighing at least 30 kg, is one tablet (150 mg of lamivudine and 300 mg of zidovudine) twice daily.

For adults weighing less than 30 kg (70 pounds), children below 12 years of age, and people with reduced kidney function, it is recommended that lamivudine and zidovudine be taken separately so each medication dose can be adjusted as needed.

Lamivudine - zidovudine may be taken with food or on an empty stomach.

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. The effectiveness of the medication depends on the right amount of lamivudine and zidovudine in the bloodstream.

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.

Do not stop taking this medication without telling your doctor.

Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children.

Each white-to-off-white, capsule-shaped, film-coated tablet, scored, embossed "GX FC3" on both sides, contains 150 mg of lamivudine and 300 mg of zidovudine. Nonmedicinal ingredients: colloidal silicon dioxide, hydroxypropyl methyl cellulose, magnesium stearate, microcrystalline cellulose, polyethylene glycol, polysorbate 80, sodium starch glycolate, and titanium dioxide.

Do not take lamivudine - zidovudine if you:

• are allergic to lamivudine, zidovudine, or any ingredients of the medication
• have a very low white blood cell count (neutropenia) or very low red blood cell count (anemia)

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.

• altered sense of taste
• dizziness
• fatigue
• gas
• general feeling of being unwell
• hair loss
• headache
• itching
• loss of appetite
• upset stomach

Although most of these 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:

• fever, chills, or sore throat
• hives
• increased frequency of infections
• muscle tenderness and weakness (severe)
• signs of anemia (low red blood cells; e.g., dizziness, pale skin, unusual tiredness or weakness, shortness of breath)
• signs of clotting problems (e.g., unusual nosebleeds, bruising, blood in urine, coughing blood, bleeding gums, cuts that don't stop bleeding)
• signs of depression (e.g., poor concentration, changes in weight, changes in sleep, decreased interest in activities, thoughts of suicide)
• symptoms of immune reconstitution inflammatory syndrome or autoimmune disorders (e.g., fever, redness, rash or swelling, fatigue, joint or muscle pain, numbness or weakness in the hands and feet spreading to the trunk, pounding heartbeat, chest pain, liver problems)
• symptoms of liver problems (e.g., nausea, vomiting, abdominal pain, weakness, diarrhea)
• tingling, burning, numbness, or pain in the hands, arms, feet, or legs

Stop taking the medication and seek immediate medical attention if any of the following occur:

• seizures
• symptoms of inflammation of the pancreas (e.g., nausea, vomiting, and abdominal pain)
• symptoms of lactic acidosis (e.g., weight loss, fatigue, generally feeling ill, abdominal pain, shortness of breath) along with an enlarged liver
• symptoms of an allergic reaction (e.g., fever; rash; nausea, vomiting, diarrhea, or abdominal pain; severe tiredness, aches, or generally feeling ill; sore throat, shortness of breath, or cough)

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.

Anemia: Pure red cell aplasia is a rare bone marrow disorder characterized by a reduction in red blood cells produced by the bone marrow. Symptoms include pallor, weakness, shortness of breath, heart palpitations, and decreased blood pressure. If you experience any of these symptoms contact your doctor immediately.

Zidovudine may also cause low levels of red blood cells without causing red cell aplasia. If you experience symptoms of reduced red blood cell count (anemia) such as shortness of breath, feeling unusually tired or pale skin, contact your doctor as soon as possible.

Fat redistribution: Over time, this medication may change how fat is distributed in your body and may change your body shape. You may notice loss of fat from the legs, arms, and face. The long-term effects of this are not known. Notify your doctor if you start developing any changes in your body's appearance.

Hepatitis B: If you have hepatitis B, your condition may worsen or recur if you stop taking this medication. Do not stop taking this medication unless recommended by your doctor. If your doctor recommends that you stop taking this medication, they will monitor you for several months after stopping treatment.

Immune reconstitution inflammatory syndrome: This medication may cause a reaction from your immune system, where signs and symptoms of inflammation from previous infections reappear. These symptoms occur soon after starting anti-HIV medication and can vary. They are thought to occur as a result of the immune system improving and being able to fight infections that have been present without symptoms (such as pneumonia, herpes, or tuberculosis). Report any new symptoms to your doctor as soon as possible.

Kidney function: Kidney disease or reduced kidney function may cause this medication to build up in the body, causing side effects. If you have reduced kidney function, 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. People with severely reduced kidney function should not take this medication.

Lactic acidosis and enlarged fatty liver: Lamivudine can cause a rare but serious condition called lactic acidosis (too much acid in the blood) along with a swollen and fatty liver. This tends to happen more often to women, especially if they are overweight. If you experience weight loss, fatigue, a general ill feeling, abdominal pain, shortness of breath, rapid breathing, an enlarged liver, or symptoms of liver problems (nausea, vomiting, abdominal pain, weakness, diarrhea), contact your doctor immediately.

Liver function: Liver disease or reduced liver function may cause this medication to build up in the body, causing side effects. Lamivudine - zidovudine may reduce liver function and can cause liver failure. 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.

Report any signs of liver problems (nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools) to your doctor immediately.

Pancreatitis (inflammation of the pancreas): This medication may cause or worsen pancreatitis, especially in children. If you have a history of pancreatitis, 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.

If you experience symptoms of pancreatitis such as abdominal pain on the upper left side, back pain, nausea, fever, chills, rapid heartbeat, or swollen abdomen contact your doctor immediately.

Reduced white blood cells: The zidovudine in this medication can cause low levels of white blood cells. This usually happens when lamivudine - zidovudine is taken for more than 4 to 6 weeks. Your doctor should order regular blood tests to monitor for changes in the numbers of blood cells during treatment. If you experience symptoms of an infection (e.g., fever, sore throat) contact your doctor immediately.

If you normally have low levels of white blood cells, your doctor may consider a different combination of medications to treat your condition.

Stopping the medication: If you stop taking this medication, your HIV infection could get worse. Take the medication exactly as prescribed by your doctor, and do not stop taking the medication without checking with your doctor first.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: Lamivudine and zidovudine pass into breast milk. If you are breast-feeding and are taking lamivudine - zidovudine, it may affect your baby. Women who have HIV infection are cautioned against breast-feeding because of the risk of passing HIV to a baby who does not have the infection.

Children: The safety and effectiveness of using this medication have not been established for children less than 12 years of age and adolescents older than 12 years of age, who weigh less than 30 kg. Lamivudine - zidovudine is not recommended for this age group.

There may be an interaction between lamivudine - zidovudine and any of the following:

• acyclovir
• atovaquone
• BCG
• cimetidine
• cladribine
• clarithromycin
• clozapine
• deferiprone
• doxorubicin
• ganciclovir
• HIV non-nucleoside reverse transcriptase inhibitors (NNRTIs; e.g., efavirenz, etravirine, nevirapine, rilpivirine)
• HIV protease inhibitors (e.g., atazanavir, indinavir, lopinavir, ritonavir, saquinavir)
• mesalamine
• methadone
• olsalazine
• orlistat
• phenytoin
• raltegravir
• ribavirin
• rifampin
• sulfasalazine
• teriflunomide
• trimethoprim
• valacyclovir
• valganciclovir
• valproic acid

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.