There can be side effects from allergy medications. Antihistamines, especially the first generation antihistamines, can cause drowsiness. They can be associated with dry mouth and in the elderly can be associated with dizziness. Oral decongestants are generally fine in most patients for short term use but they can be associated with dry mouth, anxiety, insomnia and occasional difficulty with urination. Oral decongestants should not be used in patients with high blood pressure or heart disease. Nasal decongestants should not be used for more than three days as they can cause worsening nasal congestion as the body adapts to the medication. Nasal steroids and nasal antihistamines can have an unpleasant taste and in a minority of patients can cause nasal crusting, irritation, and bleeding. Leukotriene modifiers rarely can be associated with behavior change.