High rate of adverse drug reactions with a novel tuberculosis re-treatment regimen combining triple doses of both isoniazid and rifampicin

•Triple-dose rifampicin is known to be safe for tuberculosis treatment.•Triple-dose isoniazid is known to be safe for tuberculosis treatment.•A triple dose of both rifampicin and isoniazid causes excess drug-related adverse events.•Treatment for six months throughout with four first-line drugs, all at a normal dose, is safe.