Autonomic dysreflexia (AD), also known as hyperreflexia, is a condition unique to people with spinal cord injury (SCI). The condition occurs because the pathway for nerve signals is damaged following injury. Although persons with T6 levels of injury and above are at the highest risk for AD, it does rarely occur in persons with lower levels of thoracic injuries. AD occurs as a response to some type of irritation below the level of injury. The body tries to send signals to the brain to identify and respond to the irritant, but signals are blocked by the SCI. Without communication between the brain and body, blood vessels begin to narrow and cause a rise in blood pressure. When sensors tell the brain that the blood pressure is getting too high, the brain then tries to lower the blood pressure by sending out three signals to:

  • Signal 1 – slow the heart rate (A slow heart beat is called bradycardia.)
  • Signal 2 – enlarge blood vessels above the level of injury to hold more blood. This causes the upper body to look flushed or red and blotchy.
  • Signal 3 – stop squeezing the blood vessels in the legs and abdomen.
  • However, signal 3 is blocked by the SCI, so the blood vessels keep squeezing. The blood pressure stays high. It may even keep rising. When the blood pressure gets too high, it can result in a stroke, seizure or death.


An individual may have one or more of the following signs or symptoms when experiencing an episode of autonomic dysreflexia. Symptoms may be very slight or even absent, despite a high or even very high blood pressure. Some of the more common symptoms are:

  • Pounding Headache
  • Blurred Vision
  • Flushed Face
  • Nasal Congestion
  • Red Blotches on Upper Body
  • Nausea
  • Cool, Clammy Skin
  • Chills Without Fever
  • Apprehension or Anxiety
  • Sweating Above the Level of Injury
  • Goose Bumps Above the Level of Injury
  • Slow Pulse


  • AD is usually caused by something that might ordinarily be painful, uncomfortable or physically irritating. The irritant can be anywhere below the injury level, but the source of AD is usually in a few common areas.
  • Bladder issues are the most common causes of AD. It may be bladder overfilling due to a blockage in the urinary drainage device, inadequate bladder emptying, bladder spasms, or possibly stones in the bladder. A urinary tract infection (UTI) can also cause AD.
  • Bowel issues are the second most common cause of AD. It can be an overfull bowel, constipation, or bowel blockage (impaction). Any stimulus to the rectum, such as digital stimulation, can trigger a reaction, leading to AD. Certain abdominal tests, such as a barium enema or sigmoidoscopy, can also cause AD.
  • Skin conditions such as irritations, wounds, pressure ulcers, and burns (sunburn) are possible causes. Insect bites and ingrown toenails can be triggers. Other possible causes include hard or sharp items that injure the skin, as well as tight, restrictive or wrinkled clothes. Additional triggers can vary greatly.
  • Sexual activity and overstimulation can trigger AD.
  • Severe abdominal conditions like gastric ulcers and appendicitis are possible triggers.
  • Broken bones or even extreme changes in temperature can trigger AD.
  • For women, menstrual cramps, pregnancy, labor, and delivery are potential causes.


If an individual suffers from an episode of AD, find and eliminate the cause. The first and most important step is to get into and stay in a seated position. If lying down is unavoidable, keep the head raised as high as possible. Second, check for causes of the AD, and correct any problem issue. Individuals will notice a rapid drop in blood pressure and relief in signs and symptoms when the cause is corrected. Bladder issues are the most common causes of AD, so check these potential problems first.

  • Is your drainage bag full?
  • Is there a kink in the tubing?
  • Is the drainage bag raised higher than your bladder?
  • Is the catheter clogged or plugged?

After correcting any obvious problems, individuals should change their catheter if it is not draining within 2-3 minutes. If self-catheterizing, empty the bladder and check bowel issues next. Perform a digital stimulation and empty the bowel. Stop the procedure if signs or symptoms first appear while doing digital stimulation and resume after the symptoms subside.

Finally, check other areas of concern. Loosen any tight, restrictive clothing as well as any abdominal bands or straps. Check wheelchair, bed and seat cushions for sharp objects that might be pressed into the skin causing an irritation. Be sure to look in pant pockets for keys or other objects that might be pressing on the skin.

There are certain gender specific causes of AD that need to be noted. Men need to see if there is any pressure on the testicles and/or penis, especially during sexual activity. Condom catheters need to be examined to be sure they are not too tight. Women may need to treat cramps due to contractions of the uterus before and during menstruation. Labor and delivery often will trigger AD so it is wise to be prepared in case of an episode.


Medications are generally used to treat Autonomic Dysreflexia only if the cause cannot be found and removed or when an episode continues even after removal of the suspected cause. The medications used to treat high blood pressure (also known as Hypertension) fall into two categories of Antihypertensives. Immediate medications such as Nitroglycerine Paste and Nifedipine (Procardia) rapidly lower blood pressure by widening the blood vessels to make it easier for blood to flow through them and easier for the heart to pump.

Preventative medications are used in cases of recurring AD. For example, a person who has a kidney stone may continually have high blood pressure until the stone is removed or passed. Other medical procedures or events such as child delivery can cause AD, as noted earlier. In these and other cases, you doctor may use medications to prevent AD from occurring.

Men taking medications for erectile dysfunction (ED) may have side effects (flushing in the face, headaches, nasal congestion and/or changes in vision) that also resemble signs and symptoms of AD. A blood pressure check is the best way to tell if you are having an episode of AD or side effects of the ED medication. Higher than normal blood pressure is an indication that you are experiencing an episode of AD, which is cause for you to immediately stop all sexual activity.


As with most secondary conditions in SCI, prevention is the key. Since we know what some of the triggers are for Autonomic Dysreflexia, it makes it easier to know what to do to prevent it.

Since an overfull bladder is the most common cause, it’s usually best to start there. If Foley/Suprapubic/Condom catheters are being used, be sure to keep the tube free of kinks and empty the collection bag frequently. Also, check inside of the tube frequently for any kind of grit or deposit that may indicate that you have an infection or a stone. This may be a sign that your Foley catheter needs to be changed or irritated as well. If intermittent catheterization is used, be sure to do it frequently enough to keep the bladder from filling.

The best prevention when it involves bowels is to maintain a regular bowel program. Avoid constipation by eating plenty of fiber (fruits and vegetables) and drink enough water. If hemorrhoids are present, be sure to treat them.

Do pressure reliefs frequently to avoid pressure sores. Check skin carefully every day for sores or other skin problems. Avoid wearing tight or restrictive clothing. Check clothing for sharp or hard objects that can rub or cause pressure (for example, buttons on rear pants pockets).

Refrain from long exposure in the sun and use a sunscreen to prevent sunburns. In general, avoid extreme hot or cold temperatures


A sign of AD is a rise of 20 to 40 in the baseline systolic blood pressure along with other symptoms discussed earlier. Current research shows that significant elevations in blood pressure can occur without signs and symptoms of AD (asymptomatic). This condition is known as “Silent” Autonomic Dysreflexia. To date, “Silent” AD has been studied during the time of urination, digital stimulation of the bowels, and ejaculation during sexuality in men with SCI. It appears that people at risk for AD are also at risk for “Silent” AD. However, it seems that people who have never reported having an episode of AD still experience “Silent” AD. “Silent” AD has shown to be common during some activities, and it may also prove to be common with other activities. Further research is now needed to determine whether or not “Silent” AD poses the same dangers as AD and preventive medications are needed. If you have concerns, talk with your doctor.

Individuals need a plan of action should they experience any signs or symptoms of AD. First, individuals should get in a seated position. Second, look for the cause and remove the irritation. If the cause is not found or symptoms continue, seek emergency treatment immediately. Anyone who has a spinal cord injury at or above the level of T-6 should:

Understand the signs, symptoms, causes and treatment of dysreflexia;

  • Have equipment for taking blood pressure available and know how to use it;
  • If a systolic pressure is greater than 150, it is crucial  to seek emergency treatment immediately because it can result in a stroke, seizure or death.
  • Keep a few tablets of Nifedipine (Procardia) on hand for emergencies (take only as prescribed).
  • Keep a “Medical Alert” card with you at all times, especially when away from home.
  • Be sure that all of your doctors have information about Autonomic Dysreflexia.