A common medical problem is a "head/chest cold/runny nose". When the patient is producing clear phlegm, any infection is usually caused by a virus (though can be caused by an allergy) which we cannot kill with present available medications. Bacteria often can take over, and the mucous then changes to yellow/green/brown. This is the time to visit the Surgery and antibiotics will be prescribed which should clear the bacterial infection in about 24-72 hrs. If the phlegm does not start to go clear in that time, the patient has to return for a second visit as the bacteria are resistant to that antibiotic.
It is suggested that you always keep a supply of Paracetamol (Panamax/Panadol/Dymadon/Tylenol) tablets or liquid in the house. As a general rule, if a full dose for age (2 to 3 tablets for an Adult) does not relieve pain in 45 mins., or if a child cannot sleep 45 mins. after it's full dose, medical help is usually required.
Other Useful Medical Information can be found HERE.