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. Josh Peasegood

    Hi Vero, please follow this link to a previous question to confirm that this medication is Trisbuss: https://i-base.info/qa/12098

    If this is Tribuss (a brand version of Atripla), this is a suitable medication to be used as post-exposure prophylaxis. It will help reduce your risk of HIV transmission.

  2. Vero

    My doctor give me M171 after i had an uprotected sex. Do you think is going to help me???

  3. Josh Peasegood

    Hi Dora, can I ask why you are afraid? As you have mentioned, your partner is taking his medication daily. This would likely mean that he is undetectable and cannot pass on HIV. Have you discussed this with him?


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