The standard "short" course treatment for TB is isoniazid (along with pyridoxal phosphate to obviate peripheral neuropathy caused by isoniazid), rifampicin (also known as rifampin in the United States), pyrazinamide, and ethambutol for two months, then isoniazid and rifampicin alone for a further four months. The patient is considered to be free of living bacteria after six months. For latent tuberculosis, the standard treatment is six to nine months of daily isoniazid alone or three months of weekly (12 doses total) of isoniazid/rifapentine combination.