Oral medication is not advised if a person is having trouble breathing. The person should be laid down. His or her feet should be raised above head level. However, if the person has or may have a head, neck, back, or leg injury, he or she should not be moved. The person should be covered with a blanket or coat for warmth.
Antihistamines can cause drowsiness.
Prednisone can cause stomach problems, mood swings, and sleep problems. These side effects are generally very mild. Medications used to open the airways can cause shakiness and abnormal heart rate. These, too, tend to be mild. Epinephrine can cause significant anxiety, shakiness, and abnormal heart rate.