Ask a doctor before use if you have persistent or chronic cough such as occurs with smoking, asthma, or emphysema cough accompanied by 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. These could be signs of a serious condition. sore mouth does not improve in 7 days irritation, pain, or redness persists or worsens. Warnings Sore throat warnings: if sore throat is severe, persists for more than 2 days, is accompanied or followed by fever, headache, rash, swelling, nausea, or vomiting, consult a doctor promptly. These may be serious.