4: Diseases and Drugs The pain and symptoms of certain ailments can contribute to exhaustion. Obesity, for example, can put a strain on the body's cardiovascular system, even while performing normal activities. "It's a vicious cycle," says Larry Fields, MD, a member of the board of directors for the American Academy of Family Physicians. Obesity is also associated with heart disease and diabetes, medical conditions that have fatigue as a symptom. The tiredness usually ebbs with proper management of the illness, says Fields. Be aware, however, that certain medications can have fatigue as a side effect. Some common culprits are high blood pressure pills called beta-blockers, sleep aids, antiseizure drugs, migraine drugs, and antihistamines. To clear up the problem, talk to your doctor about the possibility of reducing dosage or substituting the medicine with a similar drug.