Q. I am on Doxycycline. Will it affect my sputum report accuracy?

Answered by
Dr. Nageswara Rao
and medically reviewed by iCliniq medical review team.
This is a premium question & answer published on Aug 13, 2016 and last reviewed on: Jul 04, 2020

Hi doctor,

I am a 45 year old female. I am getting on and off cough. I have lost 5 kg in the last two years. My CT shows atypical changes and QuantiFERON TB test shows positive with a reading of 0.38. I am waiting to get my sputum test result. I am currently on Doxycycline 100 mg per day and this is my second course. I have mild breathing difficulty on exertion and has bilateral apical pleuro pulmonary thickening and scarring along with apical pulmonary infiltrates. What is my actual diagnosis?



Welcome to

  • As per your symptoms, pulmonary tuberculosis have to be ruled out.
  • Weight loss of 5 kg in two years is not significant. But, on and off cough with breathlessness is significant.
  • QuantiFERON TB is not a diagnosis of active TB, It shows latent TB.
  • Your CT findings (attachment removed to protect patient identity) favorable to pulmonary TB, maybe some healed lesions. From your sputum results you can get a definitive diagnosis.
  • You can try empirical antituberculosis treatment also.

For further information consult a general medicine physician online -->

Thank you doctor,

Currently, I am taking Doxycycline and sent a sputum sample. Does this affect my accuracy of sputum report? If my sputum result shows negative, then do I need treatment?



Welcome back to

  • Doxycycline will not affect the accuracy.
  • Even if sputum samples are negative and still you have symptoms, then you may need empirical therapy.

For further doubts consult a general medicine physician online -->

Thank you doctor,

I had whooping cough test positive. That time I had a persistent cough with a whoop sound ending and treated with Azithromycin. Can whooping cough cause lung changes such as scarring, pleural thickening and infiltration? Now my cough stopped and when I touch, both rib cages feel pain. I feel this pain for more than 5 years. Sometimes,  I feel some inflammatory pain. When I asked to my GP, he said I am a bit skinny. He advised me to use some soft pillows when I sleep. I had a history of bronchitis two to three times. I think that this might result in muscle pain. I still have that pain on my both sides. What type of pain is it? Please let me know the causes. Do I need to get isolated from my family for my current situation? Please let me know if I need isolation. My cough settled with two courses of ABS Doxycycline. Sputum stopped only producing sticky mucus with salty taste always. When I get up in the morning I can see some yellow color sputum.



Welcome back to

  • If sputum positive to TB bacilli, then only you need isolation. Otherwise, no need of isolation and wearing facemask for one to two weeks is sufficient.
  • Whooping cough may or may not be the cause of apical lung changes.
  • Your CT scan shows healed lesions.

Revert back with the reports to a general medicine physician online -->

Thank you doctor,

My three samples of sputum AFB came as negative. My specialist checked my CT film and said there is mild changes. My doctor advised me repeat AFB after 6 weeks. They did my all blood test today and will review after 6 weeks with all the results.



Welcome back to

  • It is good that AFB is negative. As I said CT findings looks old lesions (fibrotic).
  • Some infiltrates are also there. So, we need to rule out active disease.
  • You can wait for culture report. It will take minimum 3 weeks. No need of isolation now.
  • Continue the medication and complete Doxycycline course.

Revert back with the answer to the above question to a general medicine physician online -->

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