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Resistance to HIV Medicines
Resistance to HIV Medicines
Overview
Drug resistance happens when disease-causing organisms change (mutate) over time. Those changes can make the organisms survive treatment that would usually kill or control them.
Because HIV mutates often, it can easily become drug-resistant. This can make HIV harder to treat. Sometimes people become infected with HIV that is already drug-resistant.
Missing doses of your HIV medicines increases your risk of drug resistance. That's why it's important to take your medicines as directed.
When should you be tested for resistance?
You will be tested for infection with a resistant virus when:
- You are diagnosed with HIV.
- You start treatment.
- Your viral load is not going down as expected.
- Your viral load is detectable after having been at an undetectable level.
Two tests can find a resistant virus:
- A genotyping assay detects medicine resistance changes in the viral genes. This is used most often.
- A phenotyping assay measures how well viruses grow in cells with various concentrations of antiretroviral medicines. This test is rarely done. It may be used if your doctor thinks you may have a virus that is resistant to a lot of medicines.
Both of these tests are done on a sample of blood taken from a vein. These tests may not be accurate if you have not been taking your medicines for a while.
Current as of: April 30, 2024
Author: Ignite Healthwise, LLC Staff
Clinical Review Board
All Ignite Healthwise, LLC education is reviewed by a team that includes physicians, nurses, advanced practitioners, registered dieticians, and other healthcare professionals.
This information does not replace the advice of a doctor. Ignite Healthwise, LLC, disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. Learn how we develop our content.
To learn more about Ignite Healthwise, LLC, visit webmdignite.com.
© 2024-2025 Ignite Healthwise, LLC.
Related Links
HIV: Taking Antiretroviral Medicines
HIV (Human Immunodeficiency Virus) Infection
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