An irregular heart rate can be caused by a panic attack or by strong emotions, such as fear, stress or anxiety, according to WebMD. An irregular heartbeat can also be caused by intense exercise.
Some people may experience an irregular heartbeat after taking caffeine, cocaine, alcohol or other stimulants, notes WebMD. Medical conditions that can cause an irregular heartbeat include low blood pressure, anemia and fever. An irregular heartbeat may also be caused by dehydration or thyroid disease. Women may experience an irregular heartbeat due to hormonal changes during pregnancy, menstruation or the perimenopausal period.
Some medications or supplements may cause an irregular heartbeat, states WebMD. Drugs that treat an overactive thyroid or arrhythmias may cause the heart rate to change. Asthma inhalers, decongestants and diet pills may also cause palpitations. People may experience an irregular heartbeat due to abnormal electrolyte levels.
Some people may experience an irregular heart rate even if they are healthy, explains WebMD. Additional potential causes include heart disease, changes in the heart muscle, the healing from heart surgery and an injury due to a heart attack. Although some heart arrhythmias may be harmless, if a change in heart rate is noticed, request medical attention immediately.