Sore throat warning If sore throat is severe, persists more than 2 days, is accompanied or followed by fever, headache, rash, swelling, nausea, or vomiting, consult a doctor promptly. Ask a doctor before use if you have persistent or chronic cough as occurs with smoking, asthma or emphysema. cough that occurs with excessive phlegm (mucus). Keep out of reach of children. Stop use and ask a doctor if cough persists for more than 1 week, tends to recur, or is accompanied by fever, rash or persistent headache. A persistent cough may be a sign of a serious condition. sore mouth symptoms do not improve in 7 days. If pregnant or breastfeeding, ask a health professional before use.