References UK clinical guidance from the NHS, the British HIV Association (BHIVA), and the British Association for Sexual Health and HIV (BASHH). Last updated: April 2026.
Abacavir and lamivudine are nucleoside reverse transcriptase inhibitors (NRTIs) that form a common backbone of HIV treatment. They’re combined in the tablet Kivexa (abacavir 600mg + lamivudine 300mg) and used alongside a third drug (usually an integrase inhibitor) for complete HIV therapy.
The combination is found in several single-tablet regimens including Triumeq (with dolutegravir) and Dovato is a similar two-drug regimen using dolutegravir and lamivudine without abacavir.
How Do They Work?
Both abacavir and lamivudine are nucleoside analogues that block HIV’s reverse transcriptase enzyme. The enzyme mistakes them for building blocks when copying HIV’s genetic material, which stops viral replication. Using two NRTIs that target the enzyme in slightly different ways provides a robust foundation for a treatment regimen.
HLA-B*5701 Testing: Critical Before Starting Abacavir
Before starting any abacavir-containing regimen, you must have an HLA-B*5701 test. This is a genetic blood test that identifies people at risk of a serious hypersensitivity reaction to abacavir.
About 5-8% of people of European ancestry carry the HLA-B*5701 gene. In these individuals, abacavir can cause a potentially life-threatening allergic reaction with fever, rash, gastrointestinal symptoms, and respiratory problems. The reaction can be fatal if abacavir is continued or restarted after a previous reaction.
Testing is a simple, one-time blood test. If you test negative, abacavir is safe to use. If positive, your doctor will choose a different drug.
Side Effects
- Nausea
- Headache
- Fatigue
- Hypersensitivity reaction (only in HLA-B*5701 positive individuals)
- Possible small increase in cardiovascular risk (debated in research)
Lamivudine is one of the best-tolerated HIV drugs with few side effects.
Who Uses Kivexa?
Kivexa-based regimens (like Triumeq) are used as first-line treatment for people who test HLA-B*5701 negative. They’re a good choice for patients who can’t take tenofovir (due to kidney or bone concerns) and need an alternative NRTI backbone.
Read more: What is HIV? | Starting HIV treatment | Dovato
Frequently Asked Questions
What happens if I have the HLA-B*5701 gene?
Your doctor will avoid abacavir and choose a different drug. Most commonly, tenofovir-based alternatives are used. You should not take abacavir, regardless of whether you’ve had a reaction before.
Is Kivexa safer than tenofovir-based regimens?
They have different side effect profiles. Kivexa has less impact on bones and kidneys than TDF. Tenofovir has no hypersensitivity risk. Your doctor will choose based on your individual circumstances.
Related reading
- Efavirenz for HIV: An Older NNRTI Still in Use
- Eviplera: How This Anti-HIV Drug Works
- Dolutegravir: A Complete Guide to This HIV Medication
- Understanding Efavirenz in HIV Treatment
- Injectable HIV Treatment: Everything You Need to Know
Sources
- NHS — Sexual health conditions
- BASHH — UK clinical guidelines for STI management
- British HIV Association (BHIVA) — HIV treatment guidelines
- Terrence Higgins Trust — sexual health information
- UK Health Security Agency — STI surveillance data
Steve Page is a recognised expert on Sexually Transmitted Diseases (STDs) and STD treatments, having published numerous articles in peer-reviewed journals and presented his research at conferences around the world. He has an in-depth understanding of the latest medical research on STDs, and is an advocate for the development of new treatments and protocols to improve the health of those affected. In addition to his research, he has dedicated his career to understanding the causes and symptoms of STDs, as well as how to best treat those impacted.
