Study design
This is a double-blind, two-arm, randomized, placebo-controlled trial to assess the effect of ALA as an adjuvant of olfactory training on the improvement of olfactory loss in COVID-19 long-term outpatients. The study protocol was approved by the Ethics Committee of Federal University of Bahia (Ethical code: 4.562.570). All patients included in the study assigned informed consent before participation. Additionally, our trial study was approved in the Brazilian registry of clinical trials (U1111-1267-0901).