A 42-year-old man underwent cervical lymph node biopsy. After the biopsy, he suffered from an influenza A infection and was admitted to our hospital because he developed nausea, diarrhea, and shock while receiving an oseltamivir treatment. Although he was diagnosed as having tuberculous lymphadenitis and pulmonary tuberculosis and received antituberculosis therapy with isoniazid, pyrazinamide, rifampicin, and ethambutol, the symptoms other than fever did not improve. Because further examinations showed high levels of ACTH (512 pg/ml) and low levels of cortisol (≤1.0 μg/dl), along with the presence of skin pigmentation and calcification of adrenal glands on an abdominal CT scan, he was also diagnosed as having acute exacerbation of tuberculosis-associated chronic adrenal insufficiency after a viral infection. The symptoms improved rapidly with corticosteroid replacement therapy. It is important that acute adrenal insufficiency should be kept in mind in tuberculous patients who have nausea, diarrhea, or shock.