Q and A


What are the pills marked with M171 and D100?


If your doctor prescribed HIV medication that looks like the pill in the picture and has M171 embossed, this is likely to be Tribuss.


Picture: Tribuss, manufactured by Aspen.

The picture is not very clear, but M171 is one one side and D100 is on the other.

This is based on the information at this website.


Tribuss is a generic version of Atripla and it is manufactured by Aspen. It is widely used in South Africa.

Just like Atripla, Tribuss contains three active HIV drugs – efavirenz, tenofovir-DF and emtricitabine.

Sometimes Tribuss is mainly used as an HIV treatment by people who are HIV positive. However, this is an older treatment that is steadily being switched to newer drugs in many countries.

Some countries use Tribuss as a way to prevent HIV after recent risk for people who are HIV negative. This way of using HIV meds is called PEP. Tribuss is not recommended as PEP in most countries though because of the risk of side effects that are higher in people who are HIV negative.

This answer was updated in December 2019 from an orginal question posted in September 2016.


  1. Lisa Thorley

    Hi Gloria,

    If your partner is positive, there’s only a risk if his viral load is detectable. If his viral load is undetectable you’re OK. Please see here: https://i-base.info/u-equals-u/

  2. Gloria

    Hi I just found out my partner is taking m171 pills en we’ve been having unprotected sex so am so scared dat maybe I might be infected

  3. Lisa Thorley

    Hi Thandim,

    Is your partner taking ARVs? If they’re taking ARVs and their viral load is undetectable there’s no risk to you, please see here: https://i-base.info/u-equals-u/ what this means is that you don’t need to take PrEP (M171 can’t be taken as PrEP). If your partners viral load is detectable the safest thing to do is to wait, once his viral load is undetectable they’ll be no risk.

  4. Thandi

    Can I take M171 of I am HIV negative but have a partner thatnis HIV positive to prevent HIV and planning to have a child. Also will I remain HIV negative all the time?

  5. Lisa Thorley

    Hi Kholofelo,

    There’s only a risk if the person who you slept with has a detectable viral load, if their viral load is undetectable, there’s no risk. Please see here: https://i-base.info/u-equals-u/


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