Isoniazid, a central compound in the treatment of active or latent tuberculosis, is associated with various adverse reactions, including hepatitis and polyneuropathy. The latter is due to functional pyridoxine depletion and can be avoided by appropriate doses and supplementation with pyridoxine. We present the case of a patient with several previous treatment abandonments for active pulmonary tuberculosis who evolved with late postprandial vomiting due to gastroparesis documented by nuclear medicine gastric emptying tests after a new treatment onset. Gastroparesis improved with discontinuation of isoniazid and levosulpiride, reappeared with re-exposure, and improved with definitive withdrawal of isoniazid. Morbidity associated with vomiting led to prolonged hospitalization and treatment failure without the emergence of antituberculosis drug resistance. The association of gastroparesis with isoniazid was considered definitive when applying at least two causality protocols. Gastroparesis associated with isoniazid should be added to the list of adverse effects associated with this drug, even in patients receiving pyridoxine supplementation. Its recognition is initially clinical, can be confirmed with nuclear medicine studies, and affects the eradication of Mycobacterium tuberculosis.