Latent tuberculosis infection

Red Flags

Active TB must be excluded BEFORE starting LTBI treatment — symptom screen, CXR, and (where indicated) sputum smear/Xpert^[1]
Pre-existing severe liver disease — defer or avoid hepatotoxic LTBI regimens; balance individual risk^[1]
Pregnancy with LTBI — defer treatment until postpartum unless very high TB risk; avoid rifapentine in pregnancy (limited data)^[1]
Recent contact of MDR-TB case — standard LTBI regimens may not be effective; specialist input on fluoroquinolone-based prophylaxis^[1]

Active screening of high-risk groups^[1]
Household contacts of TB cases (especially children <5 and PLHIV), healthcare workers, immunosuppressed, prisoners, healthcare-associated communities

Drug	Class	Adult	Paediatric	Notes
Rifapentine + isoniazid (3HP)^[1]	Weekly rifamycin + isoniazid	Rifapentine 900 mg + isoniazid 900 mg PO once weekly × 12 doses	Per weight, age ≥2 years per NTEP/WHO	Preferred regimen for HIV-negative and select HIV-positive individuals; better completion than 6H
Rifapentine + isoniazid (1HP)^[1]	Daily 1-month rifapentine + isoniazid	Rifapentine 600 mg + isoniazid 300 mg PO daily × 28 days	Adults and ≥13 years	Shortest regimen, PLHIV indication; high completion rate
Rifampicin (4R)^[1]	Daily rifampicin × 4 months	10 mg/kg PO daily (max 600 mg) × 4 months	10–20 mg/kg/day	Alternative; better completion than 6H; consider with INH-resistance contacts
Isoniazid (6H)^[1]	Daily isoniazid × 6 months	5 mg/kg (max 300 mg) PO daily × 6 months with pyridoxine 10 mg daily	10 mg/kg/day max 300 mg	Traditional regimen; lower completion rates than shorter alternatives but still effective

Rifapentine + isoniazid (3HP)^[1]

Weekly rifamycin + isoniazid

Preferred regimen for HIV-negative and select HIV-positive individuals; better completion than 6H

Rifapentine + isoniazid (1HP)^[1]

Daily 1-month rifapentine + isoniazid

Shortest regimen, PLHIV indication; high completion rate

Rifampicin (4R)^[1]

Daily rifampicin × 4 months

Alternative; better completion than 6H; consider with INH-resistance contacts

Isoniazid (6H)^[1]

Daily isoniazid × 6 months

Traditional regimen; lower completion rates than shorter alternatives but still effective

Take LTBI treatment exactly as prescribed; missed doses or premature stop reduces protection^[1]
Watch for jaundice, severe vomiting, rash, or numb hands/feet — same-day medical review (drug toxicity); pyridoxine reduces neuropathy risk on isoniazid^[1]
Tell other clinicians and your dentist that you are on rifampicin/rifapentine — many drug interactions (oral contraceptives, anticoagulants, antiretrovirals)^[1]

Suspected active TB during LTBI workup (symptoms, CXR abnormality)TB specialist; do NOT give LTBI monotherapy alone^[1]
Contact of MDR-TB casePMDT centre for individualised prophylaxis^[1]
Severe ATT-related liver injury during LTBI therapyHospital admission; pause; sequential reintroduction under specialist^[1]

Identification and treatment of latent TB infection (LTBI) in high-risk groups; shorter rifamycin-based regimens preferred over 6-month isoniazid.

1.NTEP Guidance on TB Preventive Treatment 2024; WHO Consolidated Guidelines on Tuberculosis: Tuberculosis Preventive Treatment (2024)