Emtricitabine belongs to a class of medications called antiretrovirals, more specifically, nucleoside analog reverse transcriptase inhibitors (NRTIs). It is used in combination with other antiretroviral medications to treat human immunodeficiency virus (HIV) infection.

Emtricitabine works by interfering with enzymes that are needed for HIV to multiply, thus lowering the amount of HIV in the blood. It may also help the immune system by increasing the number of CD4 (T) cells in the body.

This medication does not cure HIV infection or AIDS and does not reduce the risk of passing HIV to others through sexual contact, sharing needles, or blood contamination.

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.

The recommended dose of emtricitabine for adults 18 years and older is 200 mg once daily taken with or without food. It is used in combination with other anti-HIV medications. If you have reduced kidney function, your doctor may recommend longer periods of time between doses.

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 that this medication be taken exactly as prescribed by your doctor. This is very important because the amount of virus in your blood may increase if the medication is stopped for even a short time, and the virus may develop resistance to this medication and become harder to treat. Do not stop taking this medication without telling your doctor. Your HIV infection may get worse if you stop this medication.

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 more than one dose of this medication in a day. 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 use this medication if you are allergic to emtricitabine or to any of the ingredients of the medication.

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.

• abnormal dreams
• cough
• diarrhea
• difficulty sleeping
• dizziness
• headache
• muscle pain
• nausea
• prickly, tingling, burning sensations
• rash
• runny nose
• skin discoloration, especially of the palms of the hands and soles of the feet
• vomiting
• weakness

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

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

• symptoms of liver problems (e.g., yellowing of the skin or eyes, dark urine, pale stools, loss of appetite, nausea, and lower stomach pain)

Seek immediate medical attention if any of the following occur:

• symptoms of lactic acidosis (e.g., nausea, vomiting, unusual muscle pain, stomach pain, weakness, tiredness, feeling cold, dizziness, lightheadedness, or irregular heartbeat)

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.

Fat redistribution: This medication may change how fat is distributed on your body. With long-term use, fat may accumulate on the stomach, back, and breasts and be reduced on the arm, legs, and face. Notify your doctor if you start developing any changes in your body's appearance.

Hepatitis B: The safe use of this medication for people who are also infected with hepatitis B has not been established. Your doctor may test you for hepatitis B infection before starting you on this medication. If this medication is used to treat HIV for people who also have hepatitis B, worsening of hepatitis B may occur. If you have hepatitis B and stop taking this medication, your hepatitis may return more severely than before. Do not stop taking this medication unless recommended by your doctor. Your doctor will monitor your liver function closely while you are taking emtricitabine.

Immune reconstitution syndrome: This medication may cause immune reconstitution syndrome, where signs and symptoms of inflammation from previous infections appear. 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, hepatitis, or tuberculosis). Report any new symptoms to your doctor immediately.

Lactic acidosis and enlarged liver: This medication can cause a rare but serious condition called lactic acidosis (buildup of lactic acid), together with an enlarged fatty liver. You may be more likely to experience these problems if you are female, obese, or have been taking nucleoside analog medications such as emtricitabine for a long time. Seek immediate medical attention if you notice any symptoms of this condition, such as:

• dizziness
• feeling cold
• irregular heartbeat
• lightheadedness
• nausea
• stomach pain
• tiredness
• vomiting

Liver problems: This medication can cause liver problems. Your doctor may monitor your liver function while you are taking this medication, especially if you have risk factors for liver problems. Tell your doctor immediately about any signs of liver problems, such as:

• dark urine
• diarrhea
• loss of appetite
• nausea
• pale stools
• vomiting
• weight loss
• yellowing of the skin or whites of the eyes

Reduced kidney function: This medication is primarily eliminated from the body by the kidneys. People with reduced kidney function will need longer than 24 hours between doses. Your doctor will recommend how you should take this medication based on your kidney function.

Pregnancy: The 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: Emtricitabine passes into breast milk. Breast-feeding is not recommended for HIV-positive women since the virus can be passed to the baby through breast milk.

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

• ganciclovir
• lamivudine
• other products that contain emtricitabine
• ribavirin
• tenofovir
• valganciclovir
• zidovudine

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.