Hi, My son was put on Singulair and Zyrtec for chronic coughing(allergies & asthma). Dr. said take him off the Singulair after a month & see how he did. He never really stopped coughing but it got worse again w/out the Singulair. So we put him back on it and around that time he had an allergic reaction to something. His mouth swelled up pretty bad. I assumed some sort of food allergy, but recently he was taken off both meds and put on Flovent for his asthma, and he has had two similar allergic reactions. My husband thinks he is adjusting to removal of the Singulair or Zyrtec from his system, but He has used them both before with no side affects. Does anyone know of lip swelling as a reaction related to these meds? We can't seem to find a common food to blame for these episodes. Thanks