Histamines are chemicals made by the body during an allergic attack and cause congestion, runny nose, sneezing and itching. Antihistamines work by blocking the histamine action, causing a reduction in symptoms. Choosing the right antihistamine most appropriate for the symptoms decreases the chances for side effects.
Dryness of Mouth
According to the Mayo Clinic, antihistamines cause a drying of the mouth, nose and throat. Frequent sips of water or melting ice chips in the mouth, provide relief of dry mouth. Chewing sugarless gum and sucking on candy are also helpful in providing assistance when dealing with dryness. If dryness persists, consult a doctor or dentist. Constant dryness of the mouth increases the chances for developing dental infections or gum disease.
Drowsiness
Most over-the-counter antihistamines cause the side effect of drowsiness. The first few doses of the medication cause the most drowsiness; additional doses aren't as problematic, reports the American Academy of Otolaryngology. Antihistamines taken at bedtime cause a less-alert mental status and even drowsiness upon arising. Some antihistamine medications cause more of a drowsiness effect than others. Therefore, practice caution by seeing how you respond to it before engaging in any activities. The American Academy of Otolaryngology recommends not operating equipment or driving an automobile while under the influence of antihistamines.The University of Maryland Medical Center recommends discontinuing the medication and seeking immediate medical care if experiencing severe drowsiness.
Other Side Effects
The Mayo Clinic warns that alcohol consumption and taking other medications in combination with antihistamines, such as central nervous system depressants, will potentiate the drug's effects. The medications include sedatives, tranquilizers, narcotics, barbiturates, medicine for seizures, muscle relaxants and anesthetics. Antihistamines may cause a skin rash with prolonged sun exposure. If an upset stomach occurs while taking an antihistamine, lessen the discomfort by taking the medication with a meal. The Mayo Clinic recommends discussing all medications that you are taking with a physician, especially when taking antihistamines. Taking antihistamines for a prolonged period of time may interact with other medications, interfere with an accurate diagnosis of a condition or affect the results of an allergy test. The University of Maryland Medical Center recommends consulting with a health care provider if any side effects arise. Obtain emergency medical care if the side effects of clumsiness or confusion, lightheadedness, a fast heart beat and shortness of breath occur while taking an antihistamine.
