Changing treatment because of resistance

The aim of HIV treatment is to lower viral load to a level that is so low that it cannot be detected by tests that look for it. This is called an undetectable viral load. The limit for detection with current tests is 50 or 40 copies/ml (depending on the test used by your clinic).

If your viral load doesn’t fall to undetectable levels and stay there, then your HIV might become resistant to some or all of the drugs used to treat it.

So if your HIV treatment isn’t lowering your viral load to undetectable levels it should be changed whenever possible.

Monitoring viral load

If you are taking HIV treatment your viral load should be checked every three months or so.

If your viral load is detectable in two consecutive tests then your treatment is not controlling your HIV and you need to change your HIV treatment.

Resistance testing

Before changing treatment you should have a test to see which drug or drugs your HIV has become resistant to. When HIV develops resistance to one drug it can also develop ‘cross-resistance’ to other similar drugs as well.

Your viral load needs to be at least 200 copies/ml for resistance tests to work.

The results of your resistance test will be looked at by an expert who will send a report to your doctor. Using this report you and your doctor will be able to choose the drugs that have the best chance of working against your HIV.

Newer drugs

The aim for everybody taking HIV treatment is an undetectable viral load.

Even if you have a lot of resistance to anti-HIV drugs there are new drugs available that give you a good chance of getting an undetectable viral load. Important drugs if you have taken a lot of treatment in the past are the boosted protease inhibitors darunavir (Prezista)/ritonavir and tipranavir (Aptivus)/ritonavir; the fusion inhibitor T-20 (enfuvirtide, Fuzeon); the CCR5 inhibitor maraviroc (Celsentri) and the integrase inhibitor raltegravir (Isentress).

It is very important to take your treatment properly. For more information see the factsheets on adherence and adherence tips.

Staying on failing treatment

Sometimes your doctor might recommend that you stay on a treatment that is failing to control your viral load. This is likely to be the case if you have no, or very few, other drug options available to you.

Your treatment might still have some effect against HIV and mean that your CD4 cell count is high enough to reduce your risk of infections.

Including 3TC (lamivudine, Epivir) in combinations that are failing to control viral load seems to be particularly beneficial.