First of all, get plenty of rest and drink lots of water and other liquids. If you are currently taking any medication or if you have a chronic medical condition, check with your physician to make sure you don't have an adverse drug interaction. Nasal sprays have the same effect, but should not be used for more than 3-5 days. Follow the recommended dosages to get continuous pain control. Remember, never give aspirin to a child.
Antihistamines block the action of histamine, a chemical that causes allergy symptoms.
Antihistamines dry out mucus membranes, so they are often used to relieve runny nose and watery eyes. Antihistamines cause drowsiness, and should be used with caution, especially if you take other medications. Expectorants loosen up phlegm and make it easier to cough up. They help clear airways and make breathing easier. Suppressants help stifle coughs due to minor throat irritation.