Substitution of a non-nucleoside reverse transcriptase inhibitor (NNRTI) with another drug of the same class combined with nucleoside reverse transcriptase inhibitors is a therapeutic strategy that can improve the tolerability of antiretroviral treatment. According to the pharmacokinetic properties of NNRTIs, this substitution generates pharmacokinetic drug interactions between NNRTIs, which could decrease NNRTI exposure and virological efficacy during the introductory phase of the new NNRTI. Pharmacokinetics and clinical data are reviewed to estimate the risk for switching from efavirenz to nevirapine, efavirenz to etravirine, efavirenz to rilpivirine and nevirapine to rilpivirine.