Adjunctive Doxycycline for Central Nervous System Tuberculosis

Inclusion Criteria: 1. Aged 21 years and above. 2. Patients receiving ≤ 7 days of TB treatment or about to start combination TB treatment, including injectable agents, where required. 3. Patients with clinical evidence of TB meningitis, as per established diagnostic criteria, defined as either definite, probable or possible CNS-TB: 1. "Definite" CNS-TB would be defined if acid-fast bacilli (AFB) or a positive nucleic acid amplification test for M. tuberculosis in the cerebrospinal fluid of patients. 2. "Probable" CNS-TB would be defined if the patient exhibit one or more of the following: suspected pulmonary tuberculosis on chest radiography, acid-fast bacilli found in any specimen other than the cerebrospinal fluid or clinical evidence of other extrapulmonary tuberculosis. 3. "Possible" CNS-TB would be defined if the patients exhibit at least four of the following: a history of tuberculosis, predominance of lymphocytes in the cerebrospinal fluid, a duration of illness of more than five days, a ratio of cerebrospinal fluid glucose to plasma glucose of less than 0.5, altered consciousness, yellow cerebrospinal fluid, or focal neurologic signs. 4. Alanine aminotransferase (ALT) level \< 3 times the upper limit of normal. 5. Able to provide informed consent. If the patient has no mental capacity to give consent, then consent may be provided for by the patient's next of kin. 6. Lumbar puncture and brain imaging (either computed tomography or magnetic resonance imaging, with or without contrast) is required at baseline for enrolment Exclusion Criteria: 1. Active Cancer 2. Pregnant or breastfeeding 3. Allergies to tetracyclines 4. Patients on retinoic acid, neuromuscular blocking agents or pimozide which may increase the risk of drug toxicity. 5. Autoimmune disease and/or on systemic immunosuppressants. 6. Use of any investigational or non-registered drug, vaccine or medical device other than the study drug within 182 days preceding dosing of the study drug or planned use during the study period. 7. Enrolment in any other clinical trial involving a systemic drug or intervention involving the CNS. 8. Contraindications to the use of steroids. 9. Investigators' assessment of lack of willingness to participate and comply with all requirements including follow-up of the protocol or identification of any factor presumed to significantly increase the participant's risk of suffering an adverse outcome.