The autonomic nervous system often becomes hyperactive in people with spinal cord injury. Autonomic dysreflexia manifests in large increases in blood pressure (hypertension) with systolic pressures exceeding 200 mm Hg, slow (bradycardia) or fast heart rate (tachycardia), headaches, facial flushing, exuberant sweating, hyperthermia, stuffy nose, goose pimples, nausea, and other signs of autonomic hyperactivity. Called autonomic dysreflexia, these episodes may be spontaneously or may be instigated by infection, pain, or other conditions that stimulate the autonomic nervous system. Severe autonomic dysreflexia may be life-threatening.

Emergency treatments of autonomic dysreflexia should initially focus on identifying potential causes that can be relieved. If the episode occurred during manipulation of the body, such as rectal stimulation, that activity of course should be stopped. The person should remain sitting and check for any blockage of bladder outflow. If necessary, place a foley catheter to drain the bladder. If the cause cannot be identified and eliminated, drugs can be used to relieve the symptoms. These include Procardia (a calcium channel blocker), nitroglycerin (a vasodilator), clonidine (alpha adrenergic agonist anti-hypertensive drug), or hydralazine (a vasodilator) to reduce blood pressure. People with spinal cord injury should carry a card with instructions to inexperienced emergency personnel.

Causes of autonomic dysreflexia may sometimes be masked by the spinal cord injury. For example, a bladder infection, kidney or bladder stones, bowel cramps, gallbladder stones, gastric ulcers, hemorrhoids, pressure sores, back pain, bone fractures, and many other potential causes may not be felt by an individual due to the spinal cord injury but may manifest in autonomic dysreflexia. Autonomic dysreflexia may result from heterotopic ossification (a condition where abnormal and painful bone growth occurs on the hip and other bones). Sometimes, back pain resulting from Harrington rods and other instrumentation may lead to autonomic dysreflexia that occur only when sitting up or lying down.

Autonomic dysreflexia often occur during sexual activity, labor, and delivery. Fortunately, the autonomic dysreflexia associated with orgasm and other sexual activity is usually mild and controllable with drugs but obstetricians should be aware and prepared to treat autonomic dysreflexia in women undergoing labor. Some individuals who have uncomfortable autonomic dysreflexia during sexual activity should consult their doctors for the possibility of having medication on had (such as nitroglycerin) to counter some of the symptoms before or after the activity. Sometimes, a glass of wine can help reduce autonomic dysreflexia.