Changing an HIV Treatment Regimen

Part of HIV and Its Treatment

Terms Used in This Fact Sheet

Clinical trial: A type of research study that tests how well medical treatments work in people.

Drug class: A group of medications that work in the same way.

Drug interaction: A change in how a drug works when taken with another drug (drug-drug interaction) or with a specific food (food-drug interaction).

Drug resistance: When HIV mutates (changes form), causing one or more anti-HIV medications to be ineffective.

Drug-resistance testing: A blood test to identify which, if any, anti-HIV medications will not be effective against a person's specific strain of HIV. Drug-resistance testing is done using a sample of blood.

Regimen: A combination of three or more anti-HIV medications from at least two different drug classes.

Treatment adherence: Closely following an HIV treatment regimen -- taking the correct dose of each anti-HIV medication at the correct time and exactly as prescribed.

Viral load: The amount of HIV in the blood. One of the goals of antiretroviral therapy is to reduce viral load.

Will my HIV treatment regimen ever change?

At some point, you may need to adjust or change your regimen. But before making any changes, it's important to understand why.

What are possible reasons for changing an HIV treatment regimen?

There are several reasons why a person may switch to another HIV regimen:

  • Side effects from anti-HIV medications
    Unpleasant side effects, such as fatigue, nausea, and diarrhea, can make treatment adherence difficult. Side effects that become unbearable or pose a serious threat to health call for a change in regimen.
  • Poor absorption of anti-HIV medications
    To work effectively, anti-HIV medications must be absorbed by the body.
  • Drug interactions
    Drug interactions between anti-HIV medications in a regimen or between anti-HIV medications and other medications a person is taking can increase the risk of side effects. Drug interactions can also reduce the effectiveness of anti-HIV medications. (Anti-HIV medications can also have the same effect on other medications.)
  • Drug resistance
    Drug resistance occurs when HIV mutates (changes form), causing one or more medications in a regimen to be ineffective.
  • Poor treatment adherence
    Skipping medications gives HIV the chance to multiply, increasing a person's viral load. Poor adherence also increases the risk of drug resistance.

What are important things to consider when selecting a new treatment regimen?

If you and your health care provider decide it's time to switch your treatment regimen, you will have many things to consider. For example, together you will review:

  • your medication history
  • any side effects from the anti-HIV medications you currently take or have taken in the past
  • results of drug-resistance testing

In general, a new treatment regimen should include two or more medications from two or more drug classes. If you are switching regimens, your new regimen may include anti-HIV medications that you have never used before.

If you have already taken many of the FDA-approved anti-HIV medications, your health care provider may recommend a new medication only available through a research study (clinical trial). To learn about participating in a research study, ask your health care provider or visit the Clinical Trials section of the AIDS_info_ website at

How can I give my new regimen the best chance of success?

Before starting your new regimen, make a commitment to keep your medical appointments and take your anti-HIV medications exactly as prescribed. Talk to your health care provider about steps you can take to overcome any lifestyle or personal issues that can make adherence difficult. (See the "Treatment Adherence" and "Following an HIV Treatment Regimen" fact sheets.)

Be sure to ask your health care provider about possible side effects from your new anti-HIV medications. Also discuss potential drug interactions between the medications in your regimen and other medications, vitamins, nutritional supplements, and herbal products that you take or plan to take.

For More Information

Contact an AIDS_info_ health information specialist at 1-800-448-0440 or visit See your health care provider for medical advice.

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.