Q and A

Question

How quickly does viral load drop on treatment?

I’ve been trying to understand on average, the daily rate of decrease in viral load following initial treatment.

I’m guessing that this changes over time and varies from case to case according to the chosen treatment, CD4 count and viral load level and possibly other factors.

However, supposing that the viral load is around 100,000, the CD4 count is around 400 and the treatment used is Atripla, could anyone please let me know the expected % decrease of viral load level per day at least within the 1st month of treatment?

Thank you for the help.

Answer

All HIV combinations (ART) starts working from the first dose.

Viral load is usually reduced by 90% (also referred to as 1 log) within the first few days. It then continues to fall but not as quickly (see below) until it becomes undetectable.

A log is a number mulitplied to the power of 10. So with a viral load of 100,000 copies/mL, a 1-log reduction would bring your viral load down to 10,000 copies/mL and a 3-log reduction would reduce it to 100 copies/mL. (See this factsheet).

You are right that individual factors will lead to difference rates of viral load reductions. These include:

  • How high your viral load was when you start ART.
  • The medicines in the combination (integrase inhibitors casuing the fastest drops).
  • The drug levels of this meds (related to adherence and how they absorb and processes drugs).
  • Good adherence – not missing doses.

UK and US guidelines recommend that your viral load should be undetectable within three months. However, many people achieve this within the first month, especailly if they are using an integrase inhibitor.

Some people take longer, especially if their viral load is very high when they start treatment.

Lots of studies have reported detailed early responses ART, including for efavirenz-based combinations like Atripla.

This decline is often referred to as having three main phases.

The first phase is very rapid – referred to in some studies as being the first few days and in others as within the first two weeks. This is where the actively infected CD4 cells are targeted. CD4 cells infected with HIV only live for a few days and when you start treatment this virus and these cells are quickly reduced.

This results in a viral load drop of perhaps 99% (2 logs) within two weeks.

The second phase, out to the first month is slower, as it is working on cells that live longer. This can easily reduce viral by another 90% (another 1 log reduction). In people with very high viral loads when they start treatment, this second phase may continue for longer until viral load becomes undetectable.

Some researchers also talk about a third phase decline which occurs even more slowly and gradually once your viral load is undetectable.

This relates to a reduction in the levels of infected CD4 cells that are latent (or resting). This pool of cells only slowly decreases over time.

This link is to an early study describing the two-phase viral load reductions.

This answer was updated in July 2020 from a question first posted on 15 September 2012.

299 comments

  1. Sisie

    Hello Lisa
    My sister has been diagnosed with HIV and TB. Her CD4Count was 28 she is very weak and is very tired she has started her treatment and has been passing yellow stool, could it be the treatment working? Cleaning out her system as she is passing yellow stool?this has been her second week on ARVs and first week on TB treatment should we be worried?. She is also taking DS24, Centrum Nd BCo tablets to boost her immune system.Thank you as you reply

  2. Lisa Thorley

    Hi Nomvula,

    What’s your viral load now? What did it use to be? How long have you been on meds?

    The only thing that can control a persons HIV, so their CD4 count and viral load is medication. No supplement can help this.

  3. Nomvula

    hi Lisa what supplements can I get for high viral load ; the CD4 count is ok but only the viral load has increased and I am not taking any supplements for now

  4. Lisa Thorley

    Hi Kim,

    The only thing that can decrease your viral load and increase your CD4 is ARVs. Supplements can’t help this. Are you on treatment?

  5. Kim

    I would like to know what supplements can I take to decrease my viral load that won’t affect my CD4 count but to increase the CD4 count at the same time?

  6. Lisa Thorley

    Hi Nohlanhla,

    Its fine to take your meds a few minutes after your normal time, and even a few hours. For more info please see Q4 here:

    https://i-base.info/qa/what-are-the-most-asked-questions

  7. Nohlanhla

    What happens if I take my meds a few minutes later than normal?

  8. Lisa Thorley

    Hi Kingsley,

    Taking your meds as you’re doing is fine, it won’t effect your viral load, or CD4 count.

  9. KINGSLEY

    Hi Lisa,

    Am Kingsley, from Nigeria. Want to ask a question, is my viral load and CD4 count going to be affected negatively owing to the time frame I take my med? I do take my med between 11:30pm to 12:00am. I have never missed since a month ago I started.

  10. Lisa Thorley

    Hi Nelly,

    Try not to panic. You’ll be OK. Yes the drop is a lot, but this is what can happen when you aren’t on treatment. What you need to do now is arrange to start treatment. Its the being on ARVs that will control your HIV. What this means is that your viral load will become undetectable, (less than 50) and your CD4 will rise.

    For more about starting treatment, please see here:

    http://i-base.info/guides/starting

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