Terms Used in This Fact Sheet

Drug resistance: HIV can mutate (change form), resulting in HIV that cannot be controlled with certain medications. Toxicity: the harm a medication can do to your body. Viral load: the amount of HIV in a sample blood.

What Is Regimen Failure?

Regimen failure occurs when the anti-HIV medications you are taking do not adequately control the infection. Factors that may cause regimen failure include:

• Poor health before starting the treatment regimen

• Poor adherence to the regimen (not taking medications exactly as instructed by your doctor, missing doses)

• Previous HIV treatment and/or drug resistance

• Alcohol or drug abuse

• Side effects of medications, drug toxicity, or interactions with other medications

• Medication poorly absorbed by the body

• Medical conditions or illnesses other than HIV infection

What Are the Three Types of Regimen Failure?

1. Virologic failure: Regimens should lower the amount of HIV in your blood to undetectable levels. Virologic failure has occurred if HIV can still be detected in your blood 48 weeks after starting treatment, or if it is detected again after treatment had previously lowered your viral load to undetectable.

2. Immunologic failure: An effective regimen should increase the number of CD4 cells in your blood or at least prevent the number from going down. Immunologic failure can occur even if your viral load remains undetectable.

3. Clinical progression: Clinical progression has occurred if you experience an HIV-related condition or a decline in physical health despite at least 3 months of HIV treatment.

Virologic failure is the most common kind of regimen failure. People with virologic failure who do not switch to a more effective treatment regimen usually progress to immunologic failure within about 3 years. Immunologic failure may be followed by clinical progression.

What Happens If My Regimen Fails?

If your treatment regimen fails, your doctor will evaluate your treatment history, medication side effects, problems you may have had with taking the medications as directed, your physical condition, and results of drug resistance testing to determine why your regimen is failing. You and your doctor may then select a new treatment regimen to better control your infection. See Changing My HIV Treatment Regimen Fact Sheet for more information about changing treatment regimens.

For More Information

Contact your doctor or an AIDSinfo Health Information Specialist at 1-800-448-0440 or http://aidsinfo.nih.gov.

This information is based on the U.S. Department of Health and Human Services' Guidelines for the Use of Antiretroviral Agents in HIV-1-Infected Adults and Adolescents (available at http://aidsinfo.nih.gov).