Resistance / Treatment failure

Unfortunately, anti-HIV drugs can lose their effectiveness over time. The virus can stop responding to the active ingredients and begin to replicate in the body again. When this happens, we say that the virus has developed resistance.

If the treatment is no longer effective, the amount of virus in the body (viral load) begins to rise again and HIV can once again damage the immune system. This is called treatment failure. In this case, a new combination of drugs must be used.

As there are many different medications to fight HIV today, this is usually possible. On the other hand, there is not an unlimited number of possibilities. The development of resistance should be avoided as much as possible.

How does resistance develop?

HIV medications function best when a sufficient amount of their active ingredients is present in the body. Sometimes, however, that is not the case.

There are different reasons for this: maybe you have forgotten to take your medication regularly, or perhaps the drugs were broken down unusually quickly by the liver. Diarrhea or vomiting after taking the medication can also cause an insufficient amount of the active ingredients to reach the body.

The virus can then begin to replicate again. In addition, new variations on the virus can develop by chance, and the drugs you are on may not work against these new strains. The new virus is able to multiply unchecked.

In the end, the treatment you are on is not effective against most of the virus in your body. The virus has become resistant. One or more of the prescribed drugs is no longer effective as HIV treatment in this situation.

Over time, unfortunately, drug resistance develops in almost all people. If drug resistance occurs, it does not necessarily mean that you have done something wrong when taking the medication.

Drug-resistant virus can also be transmitted. That means that some people are infected with a strain of HIV that is already resistant to certain drugs.

Resistance test

A blood test can determine which drugs are still working and which ones a person is resistant to. This test is done before starting HIV therapy or when a change in the drug combination is planned.

Avoiding resistance

Treatment for HIV only works effectively when it is taken regularly and at the right time. With some drugs, you may also need to follow some dietary requirements. Some drugs have to be taken on an empty stomach; others should be taken with a meal, for example.

In addition, it's important you discuss any other medications or drugs you are taking with your doctor in case they interact with your HIV treatment. Other medications can lead to the HIV drugs being broken down more quickly in the body, which can lead to resistance.

If you have difficulty taking your drugs regularly, you should discuss this with your doctor. Sometimes it is possible to change to other drugs that are easier to take.

Therapy options in the case of drug resistance

There are now many drugs used to combat HIV, and numerous possible combinations. It is usually possible to change to other HIV drugs when resistance develops. Resistance does not mean an end to HIV therapy!

It is sometimes the case, however, that resistance to one drug also leads to resistance to another similar drug. This is called cross-resistance. It limits the choice of follow-up therapy.

In addition, the number of drug combinations is always increasing thanks to research, but it is not unlimited. It is therefore sensible to try to delay the development of resistance as long as possible, to keep as many therapy options open as possible.