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TB - Should I do the treatment?



After a recent positive TB test, diagnosed as inactive TB, my pulmonologist prescribed INH treatment for 6 months. X-ray and CAT scan showed no TB. In 1946, at age 13 I was told that I had a "shadow" on my lung and sent for 6 weeks to a TB hospital on the Baltic Sea in Germany for fresh air and rest. I understand that only 10% of patients develop active TB. Since I have not developed active TB in 52 years, I am reluctant to take the treatment because of side effects. I would appreciate your opinion. Thank you.


The risk of developing tuberculosis after an exposure to TB ranges from 5-10% depending on how long ago the exposure occurred. If, as you believe, your exposure to TB occurred in the 1940's then your risk of TB in the future is about 5% or 1 in 20, provided you have no additional health problems.

The 5% risk can increase depending upon other health problems. The diseases that are known to increase the risk of TB are: diabetes, being on dialysis, HIV infection, taking certain medications that suppress the immune system, having fibrosis on the chest xray consistent with TB in the past, having an active cancer of the blood or lymph system.

Ultimately taking isoniazid preventive therapy is a personal decision. As you get older there is a risk of developing liver inflammation from Isoniazid of about 1%. So, when I see patients like you, I review the risk of TB (5%) assuming no other health problems, versus the risk of the medication (1%) and allow the patient to decide which risk bothers them more. IE, are you more worried about getting TB, or are you more worried about taking the medication.

For more information:

Go to the Tuberculosis health topic, where you can:

Response by:

Catherine A Curley, MD, MS Catherine A Curley, MD, MS
Assistant Professor of Medicine
School of Medicine
Case Western Reserve University