Limiting the chance of resistance

Whenever HIV is still able to reproduce in the body of someone who is taking anti-HIV drugs, it is extremely likely that resistant strains will eventually emerge. The selection of as potent a drug regimen as possible tends to delay the onset of resistance, because viruses that are resistant to the effects of one of the drugs may still be controlled by the others.

After six years of treatment 38% of people had experienced viral rebound, according to a review of 4306 HIV-positive people attending six British HIV clinics. 1 2 The risk of a major mutation over this time period was 27%, while 20% of people developed resistance to at least two of the three main drug classes.

Ritonavir-boosted PI-based regimens had a significantly lower risk of resistance mutations than NNRTI-based regimens; this finding has been confirmed by other studies. 3 4 NNRTI-based combinations have a lower risk of resistance compared to single PI therapy after controlling for factors such as baseline viral load and adherence; 5 however, unboosted PI therapy is now rarely used in practice.


  1. Phillips AN et al. Risk of development of drug resistance in patients starting antiretroviral therapy with three or more drugs in routine clinical practice. Antivir Ther 9: S151, 2004
  2. UK CHIC Study Group. Long-term probability of detection of HIV-1 drug resistance after starting antiretroviral therapy in routine clinical practice. AIDS 19: 487-494, 2005
  3. Harrigan PR et al. Predictors of HIV drug-resistance mutations in a large antiretroviral-naive cohort initiating triple antiretroviral therapy. J Infect Dis 191: 339-347, 2005
  4. Von Wyl V et al. Emergence of HIV-1 drug resistance in previously untreated patients initiating combination antiretroviral treatment: a comparison of different regimen types. Arch Intern Med 167: 1782–1790, 2007
  5. Bangsberg D et al. 95% adherence is not necessary for viral suppression to less than 400 copies/ml in the majority of individuals on NNRTI regimens. Twelfth Conference on Retroviruses and Opportunistic Infections, Boston, abstract 616, 2005
Community Consensus Statement on Access to HIV Treatment and its Use for Prevention

Together, we can make it happen

We can end HIV soon if people have equal access to HIV drugs as treatment and as PrEP, and have free choice over whether to take them.

Launched today, the Community Consensus Statement is a basic set of principles aimed at making sure that happens.

The Community Consensus Statement is a joint initiative of AVAC, EATG, MSMGF, GNP+, HIV i-Base, the International HIV/AIDS Alliance, ITPC and NAM/aidsmap

This content was checked for accuracy at the time it was written. It may have been superseded by more recent developments. NAM recommends checking whether this is the most current information when making decisions that may affect your health.

NAM’s information is intended to support, rather than replace, consultation with a healthcare professional. Talk to your doctor or another member of your healthcare team for advice tailored to your situation.