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.
Raltegravir (brand name Isentress) was the first integrase strand transfer inhibitor (INSTI) approved for HIV treatment, licensed in 2007. It blocks the enzyme HIV needs to insert its DNA into human cells, effectively stopping the virus from establishing infection. Although newer integrase inhibitors (dolutegravir, bictegravir) are now preferred as first-line therapy, raltegravir remains an important option.
How Does Raltegravir Work?
After HIV enters a cell and reverse-transcribes its RNA into DNA, the virus uses integrase to insert this DNA into the host cell’s genome. Raltegravir blocks the “strand transfer” step of integration, preventing HIV DNA from becoming part of the cell’s DNA. Without integration, HIV cannot replicate.
Dosage
- Standard: 400mg twice daily with or without food
- Once-daily formulation: 1200mg (2 x 600mg tablets) once daily with or without food
- Always taken with at least two other antiretroviral drugs
Side Effects
Raltegravir is generally well tolerated:
- Headache (common)
- Nausea
- Diarrhoea
- Fatigue
- Insomnia
- Rarely: rash, liver enzyme elevation, muscle pain
Raltegravir vs Newer Integrase Inhibitors
| Feature | Raltegravir | Dolutegravir | Bictegravir |
|---|---|---|---|
| Dosing | Twice daily (or once with 1200mg) | Once daily | Once daily |
| Resistance barrier | Lower | Very high | Very high |
| Drug interactions | Minimal | Minimal | Minimal |
| Weight gain | Low | Higher | Higher |
| First-line use | Occasional | Preferred | Preferred |
Read more: What is HIV? | Starting HIV treatment
Frequently Asked Questions
Is raltegravir still used?
Yes, though less commonly as first-line treatment. It’s sometimes preferred for patients who experience weight gain on dolutegravir, in pregnancy (when long-term safety data matters), or when drug interactions make other INSTIs unsuitable.
Does raltegravir cause weight gain?
Raltegravir is associated with less weight gain than dolutegravir and bictegravir. This is one reason some patients prefer it.
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.
