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Combivir

Combivir is a combination medication that contains lamivudine, and zidovudine. It is used with other antiretroviral agents as a part of antiretroviral therapy (ART) for HIV-1 in individuals who are at least 66 pounds (30 kg). Although it is not a cure for HIV, when taken as directed, it allows for the virus to be suppressed. This prevents further transmission of HIV and allows an individual’s immune system to improve through increasing CD4 cell counts and decreasing the amount of active virus in the blood (viral load).

What are the ingredients in Combivir?

The main ingredients in Combivir are lamivudine and zidovudine. Both ingredients are nucleoside reverse transcriptase inhibitors (NRTIs).

How does Combivir work?

Combivir is a combination of two NRTI medications. NRTIs stop the reverse transcription step of the HIV life cycle. Normally, HIV uses its reverse transcriptase enzyme to build a strand of DNA from its original RNA form. In order to do this, it uses genetic building blocks called nucleosides that come from the host cell. These nucleosides are strung together one at a time, like beads on a string, to create the final DNA product.

NRTIs act as nucleoside mimics that stop the DNA-building process. NRTIs look like normal nucleosides, except they’re missing a special chemical group on one side. Without this group, the reverse transcriptase enzyme is unable to attach more nucleosides to the chain after them. This prevents the full string of DNA from being formed, preventing HIV RNA from making it all the way through the reverse transcription process and into host DNA for further replication.

What are the possible side effects of Combivir?

The most common side effects of Combivir include, but are not limited to:

  • Nausea
  • Headache
  • Weakness
  • Tiredness
  • Diarrhea
  • Cough
  • Nasal symptoms

Things to note about Combivir

As with any medication, there are several very rare but serious risks that need to be considered before taking Combivir. Your healthcare provider can help determine what issues you may be at risk for and help determine what treatment options are the safest for you. It’s also important to remember that the risk of one or more of these issues occurring is low, and the benefits of treating the virus often greatly outweigh the risks.

Rarely, Combivir may impact an individual’s red and white blood cells. Low red blood cell counts (anemia) and low numbers of a specific kind of white blood cell called neutrophils (neutropenia) may occur. This is especially true for individuals with more advanced HIV. Blood counts should be regularly monitored while taking Combivir. Combivir may also cause muscle weakness or pain, called myopathy. If you have hepatitis B virus and start taking Combivir, your hepatitis B may get worse.

Other rare but serious side effects of Combivir include liver issues and an increase of lactic acid in the blood (lactic acidosis). Signs of liver issues include, but are not limited to:

  • Dark-colored urine
  • Loss of appetite
  • Nausea
  • Yellowing of the whites of the eyes or skin
  • Light-colored bowel movements
  • Pain or tenderness on the right side of your stomach

Signs of lactic acidosis include, but are not limited to:

  • Trouble breathing
  • Feeling cold, especially in the limbs
  • Dizziness or lightheadedness
  • Feeling tired or weak
  • Muscle pain
  • Nausea and vomiting
  • Irregular or fast heartbeat

Before starting Combivir, tell your doctor if you:

  • Have or previously had hepatitis B virus
  • Have or previously had hepatitis C virus
  • Have low blood cell counts or a history of a bone marrow or blood disorders
  • Have a history of liver, pancreas, muscle, or kidney problems
  • Are pregnant or planning to become pregnant
  • Are breastfeeding or planning to breastfeed
  • Are taking any over-the-counter vitamins, supplements, medicines, or herbal remedies
  • Are on any other medications or are about to start any other medications, including hormonal birth control or medications for hepatitis viruses

Combivir may cause a condition called IRIS (immune reconstitution inflammatory syndrome). IRIS occurs when an individual’s immune system gets stronger after being weak and responds aggressively to previously hidden infections. This heightened response may make the person fighting the infection feel worse. Alert your healthcare provider immediately if you begin to have new symptoms after taking Combivir.

On rare occasions, Combivir may cause changes in body fat, especially around the breast, trunk, upper back, and neck regions.

Combivir may also increase an individual’s risk of developing pancreatitis, or inflammation of the pancreas. Your healthcare provider can help determine if you are at risk for this rare but serious side effect.

Dosing information

The most common dosage of Combivir is one tablet taken by mouth two times a day for adults and adolescents, and one tablet two times a day for children. A tablet contains 150 mg of lamivudine and 300 mg zidovudine. It is important to take your medication exactly as prescribed; do not stop or change your Combivir dosage without talking to your healthcare provider first.

Combivir can be taken with or without food. If you miss a dose of Combivir, take the next dose as soon as you remember; however, never take two at a time. If it is close to your next dosage time when you remember, just take your next dose only. If you take too much Combivir, seek medical attention immediately.1,2

Written by: Casey Hribar | Last reviewed: September 2019
  1. Combivir. United States Department of Health and Human Services: AIDSinfo. https://aidsinfo.nih.gov/drugs/285/combivir/0/patient. Published November 7, 2018. Accessed July 20, 2019.
  2. Combivir Prescribing Information. GlaxoSmithKline. https://www.gsksource.com/pharma/content/dam/GlaxoSmithKline/US/en/Prescribing_Information/Combivir/pdf/COMBIVIR.PDF. Published May 2019. Accessed July 20, 2019.