Antihistamines refer to a type of medication used to manage such allergy manifestations as a runny nose, itchy or watery eyes, nasal congestion, chest congestion, itching, a rash and sneezing. A potentially life-threatening condition called anaphylaxis can result if allergy symptoms are left untreated. Difficulty breathing, hives and swelling up of the throat characterize anaphylaxis. Fortunately, antihistamine drugs are utilized to treat allergy symptoms.
Fexofenadine
Fexofenadine blocks the action of histamine in the body. Histamine is a substance released from mast cells to promote allergy symptoms. According to Drugs.com, fexofenadine is specifically used to treat seasonal allergies and chronic idiopathic urticaria (hives and skin itching that have no apparent cause). Drugs.com says that fexofenadine's side effects include menstrual cramping, diarrhea, nausea, stomach problems, fatigue, drowsiness, back or muscle pain and headache. Fexofenadine comes in tablet and liquid form. It should not be used with antacids or fruit juices, as they can interfere with the drug's absorption into the body.
Hydroxyzine
Hydroxyzine is used to reduce contact dermatitis and hives. Drugs.com says that hydroxyzine is also a sedative medication that works on the central nervous system (brain and spinal cord), as it reduces anxiety and tension. It also manages nausea and vomiting. Drugs.com indicates that hydroxyzine's side effects include drowsiness, dizziness, blurry vision, headache and dry mouth. This drug's serious effects include tremors, confusion, seizures and increased movement of the neck, eyes, tongue or jaw. A woman should not take hydroxyzine while pregnant, as it can cause serious harm to the unborn baby.
Diphenydramine
According to MedlinePlus, diphenhydramine treats cough, insomnia, motion sickness and abnormal movement in addition to common allergy symptoms. The drug's side effects include dry mouth, throat or nose; dizziness; nausea; vomiting; nervousness; headache; constipation and loss of appetite. Muscle weakness, chest congestion, excitement, visual problems and problems urinating are diphenydramine's other side effects, as noted by MedlinePlus. Diphenydramine can be taken as a capsule, dissolving tablet, liquid or dissolving strip.
