Thanks for the question. Cough accompanied by night sweats brings to mind a couple diagnostic possibilities. The classic diagnosis for these symptoms is tuberculosis (TB), though this would require exposure; exposure to tuberculosis happens in countries where TB is common (such as India), or exposure to homeless or prison populations. However, cough and night sweats could be caused by many other things. Smoking increases the risk for lung infection, and also can by itself cause problems such as emphysema and bronchitis (though your son would be young for these to be present as of yet). Stopping smoking is the first step to improving cough and his overall health. As for HIV, cough and night sweats are symptoms of HIV, but per your report your son has limited exposure (heterosexual, one partner). However, unprotected sex means there is always a possibility of contracting HIV, and your son should probably be re-tested. I hope this helps. Dr. Sheppe