I've heard a few folks complain that they're experiencing a dry,
irritated throat recently. When sbst275 asked for advice on what
meds to take for his irritating cough, I thought it might be
helpful to include some basic info on cough syrups in here.
Please, the advice here does NOT replace a sensible visit to the
doc! 
It's just for general
knowledge!
Cough syrups can generally be categorised in two broad categories :
EXPECTORANTS or COUGH SUPPRESSANTS.
EXPECTORANTS
If you have a lot of mucous clogging up your breathing airway,
expectorants will help to thin the mucous and make it easier to
cough out. Basically, expectorants are given for coughs that sound
very 'wet'. The main expectorant used is guaifenisin, available
under many brand names.
There are other ways to loosen and clear the respiratory secretions
associated with colds. These include using a humidifier and
drinking six to eight glasses of water a day.
Side effects are not common, and may include vomiting, diarrhea,
stomach upset, headache, skin rash, and hives.
COUGH SUPPRESSANTS
If you have a 'dry' and irritating cough that won't seem to stop, a
cough suppressant will provide relief because it will help lessen
the coughing episodes. It helps to suppress those cough episodes so
you'll be able to sleep better at night. The active ingredient in
most cough suppressants is dextromethorphan, available under many
brand names.
You may experience the side effects of drowsiness, nausea,
vomiting, stomach upset, and dizziness.
If you have a cough that lasts more than seven days, or are
associated with fever, rash, sore throat, or lasting headache, you
should pay a visit to the GP!
Take care and good health to all! 
