TB Preventive Therapy: Simple Facts You Need to Know

Got a positive TB test but no active disease? That’s called latent TB infection (LTBI). You’re not sick, but the germs are hanging out in your lungs, waiting for a chance to cause trouble. TB preventive therapy (also called LTBI treatment) is the plan that helps your body clear those germs before they turn into active TB.

Why bother? Because active TB can damage lungs, spread to others, and even be fatal if untreated. A simple course of medication cuts that risk dramatically. In most high‑income countries, doctors recommend preventive therapy for anyone with a positive test who falls into a higher‑risk group—like recent contacts of active cases, people with HIV, or those starting immune‑suppressing meds.

Who Should Start Preventive Therapy?

Not everyone with LTBI needs treatment, but the following groups usually get a green light:

• People who have been in close contact with someone who has active TB.
• Anyone living with HIV or other conditions that weaken the immune system.
• Patients about to start chemotherapy, organ transplant, or high‑dose steroids.
• Children under 5 years old who test positive.
• Those coming from countries where TB is common.

If you fit any of these categories, talk to your doctor about a preventive regimen.

Common Drug Regimens and How to Take Them

There are a few tried‑and‑true options. The best one for you depends on your health, how well you can stick to the schedule, and any drug‑interaction concerns.

• Isoniazid (INH) for 6–9 months: The oldest and most widely used. Take a pill daily, usually with vitamin B6 (pyridoxine) to stop nerve problems.
• Rifampin (RIF) for 4 months: Shorter than INH and works well for people who can’t tolerate the longer course.
• Weekly Isoniazid + Rifapentine (3HP) for 12 weeks: A once‑a‑week dose observed by a health worker. Great if you want a quick finish.

All regimens require a blood test before you start to make sure your liver is healthy. Your doctor will repeat the test after a few weeks, especially if you’re on the longer INH schedule.

Side effects are usually mild—maybe a little nausea, headache, or a rash. The big worry is liver irritation. If you notice dark urine, yellow skin, or severe fatigue, call your clinic right away.

Staying on track is easier when you set reminders, use a pillbox, or pair the dose with a daily habit like brushing teeth. Many clinics also offer short‑term video check‑ins to keep you accountable.

In short, TB preventive therapy is a short, safe, and effective way to stop a silent infection from turning into a serious disease. If you’ve tested positive for latent TB, ask your provider which regimen fits your life best and get started today.