You can't drink coffee and medicine at the same time.

The Hong Kong Institute of Pharmacists warned that cold medicines commonly contain phenylpropanolamine, which may cause a sharp rise in blood pressure if taken together with high caffeine products, which may be fatal.

Members of the public are also not allowed to take medicine with coffee or tea. They should consult a pharmacist before taking medicine.

PPA is a commonly used oral medicine. There are 85 registered medicines containing PPA in Hong Kong, most of which are combination cold medicines, including over-the-counter medicines generally available in pharmacies. The Society of Pharmacists cites foreign studies showing that PPA can triple maximum blood concentrations when taken in conjunction with high caffeine products.

The Education Director of the Pharmaceutical Education Resource Centre of the Hong Kong Institute of Pharmacists, Mr Tsui Chun-ming, pointed out that a single dose of cold medicine contains about 25 mg of PPA. If taken three to four times together with 400 mg of caffeine products, there is a chance that blood pressure will rise sharply and critical symptoms such as severe headache, nervousness and shortness of breath will occur, requiring blood pressure lowering treatment. Some patients with uncontrolled hypertension or stroke may be life threatening.