A persistent cough may be a sign of a serious condition. Keep this and all medications out of the reach of children. In case of accidental overdose contact a medical professional or Poison Control Center immediately. Stop use and ask a doctor if: symptoms persist for more than 7 days or worsen symptoms are accompanied by high fever (101°F) cough tends to recur or is accompanied by high fever, rash or persistent headache. Warnings Do not use: for persistent or chronic cough such as occurs with asthma, smoking or emphysema if cough is accompanied by excessive mucus, unless directed by a licensed health care professional.