Popular cold and allergy remedies often contain a combination of antihistimines and decongestants. Side effects for these medicines range from drowsiness to sleeplessness, and may not be advisable for patients with hypertension, or thyroid disorders. Decongestants often have a stimulant effect. If a particular decongestant makes a child with allergies seem hyperactive, a parent may be able to solve the problem by switching to a different decongestant medicine. However, to do this the person buying the medicine must know exactly what kind of decongestant or antihistamine they are getting.
Many antihistamines have the opposite effect, causing drowsiness.
There is a new generation of antihistamines, which is currently available by prescription, that does not cause this side effect. Another medicine which may be taken to help clear up mucus is called an expectorant. These medicines simply thin the mucus secretion so that it can drain or be loosened by coughing. Drinking plenty of water or other liquids can help to achieve the same results. Sinus headaches are a familiar symptom to allergy sufferers, resulting when pressure builds up in nasal cavities.