Truvada (TDF and EM) + Sustiva (Efavirenz)

There is no harmful interaction expected between the two drugs. They work well and can be coadministered. Although these drugs can be used together, a doctor’s prescription is highly recommended.

What Is Truvada Used For?

Truvada is a highly potent drug prescribed for use in the following cases:

  • HIV-1 infection treatment in combination with another antiretroviral med to fully combat virus multiplication in the body;
  • as PrEP – for preventing HIV infection in people who are HIV negative and at a high risk of getting the virus [1];
  • as PEP in emergency situations (started within 72 hours after a possible exposure to the virus) to lower the chances of HIV getting into the blood cells [2].

Truvada has two active substances: emtricitabine (EM) and tenofovir-DF (TDF) that belong to the NRTI drug class.

Uses of Sustiva (Efavirenz)

Sustiva is a powerful first-line antiretroviral medication belonging to a class of NNRTIs and having efavirenz as an active substance. It’s used to treat HIV in combination with other NRTI or protease inhibitor.

This highly effective med reduces viral load (HIV-1) substantially in six months in 60 to 80% of treatment-naïve patients. Efavirenz is not active against HIV-2 [3].

Drugs Interaction: Truvada and Sustiva Stack

While there is no significant drug interaction between these two meds, clinical tests show a very minimal interaction between individual active substances.

From a study based on 9 treatment-naïve patients, when coadministering efavirenz and emtricitabine in the presence of didanosine, the pharmacokinetics of emtricitabine were not affected. In contrast, didanosine Cmax and AUC were higher than expected, and efavirenz Cmin, Cmax, and AUC were lower than expected.

Coadministration of efavirenz and tenofovir-DF decreased efavirenz AUC and Cmax both by 4%. TDF Cmax increased by 7% and AUC decreased by 1%. From these clinical results, there is no need for dosage adjustment of efavirenz when coadministered with Truvada [4].

While taking these meds concomitantly, a doctor’s supervision is necessary. Efavirenz can cause liver problems, and using it with TDF/EM or any other med known to induce hepatotoxicity may increase that risk. Avoid or limit the use of alcohol while being medicated with these drug stack [5].


  1. Emtricitabine / Tenofovir Disoproxil Fumarate.
  2. Current perspectives in HIV post-exposure prophylaxis. Binta Sultan, Paul Benn, and Laura Waters. HIV AIDS (Auckl). 2014; 6: 147–158. Published online 2014 Oct 24. doi: 10.2147/HIV.S46585.
  3. Efavirenz (Sustiva).
  4. Pharmacokinetics of emtricitabine, didanosine, and efavirenz administered once-daily for the treatment of HIV-infected adults (pharmacokinetic substudy of the ANRS 091 trial). Molina JM, Peytavin G, Perusat S, Lascoux-Combes C, Sereni D, Rozenbaum W, Chene G. HIV Med. 2004 Mar;5(2):99-104.
  5. Drug Interactions between Sustiva and Truvada.
It may be useful for you