Autonomic Dysreflexia: Recognition, Response & Prevention

What Is Autonomic Dysreflexia?

Autonomic dysreflexia (AD) — sometimes called autonomic hyperreflexia — is a potentially life-threatening condition in people with spinal cord injuries at or above T6. It's an uncontrolled, exaggerated response of the autonomic nervous system to a painful or irritating stimulus below the level of injury.

The result is a sudden, dangerous spike in blood pressure — often rising to 200/100 mmHg or higher — that, if not quickly resolved, can cause hemorrhagic stroke, seizures, heart attack, or death.

AD is common. Most people with T6-and-above injuries experience it. Managing it is a core survival skill, not an edge case.

Who Is At Risk

Anyone with a spinal cord injury at T6 or above is at risk for AD. The higher the injury, the more of the body's vascular system is below regulatory control, and the more severe the potential blood pressure response.

Some people with T7–T10 injuries also experience AD, though typically less severe. If you have a thoracic or cervical injury, assume you are at risk until your physiatrist tells you otherwise.

People with incomplete injuries can still have AD — preserved partial sensation doesn't eliminate the reflex. Many people with central cord syndrome experience AD.

What's Happening in Your Body

Normally, when something painful happens below your injury, your nervous system sends a distress signal upward through the spinal cord to the brain, which regulates the response and prevents blood pressure from spiking uncontrollably.

With a T6 or above injury, that regulatory signal can't get back down through the cord to where it's needed. So the body's initial response — a massive sympathetic (fight-or-flight) activation that constricts blood vessels and drives up blood pressure — runs unchecked below the injury. Your blood pressure spikes. Your brain tries to compensate by slowing your heart rate (which is why your pulse may slow during AD even as pressure rises). But the pressure keeps climbing until the triggering cause is removed.

The baseline blood pressure for many SCI patients is lower than average (often 90–110/60 mmHg). A rise of 20–40 mmHg systolic above your personal baseline signals AD — you don't need to hit 200 for it to be dangerous.

Common Triggers

AD can be triggered by anything that would normally cause pain or discomfort below the level of injury — even if you cannot feel it. The most common:

Bladder — #1 cause

• Overdistended bladder (missed catheterization, kinked catheter tube, blocked Foley)
• Full leg bag with drainage blocked
• Bladder spasms or overactive bladder contractions
• Urinary tract infection
• Urodynamics testing (a known AD trigger — your urologist should be prepared)

Bowel — #2 cause

• Constipation or fecal impaction
• Digital rectal stimulation during bowel program
• Gas or bowel distension
• Inflamed hemorrhoids

Skin & Pressure

• Pressure injury (even a Stage I you can't feel)
• Ingrown toenail
• Tight clothing, shoes, or leg straps
• Sitting on a wrinkled garment or object
• Burns or sunburn below injury level
• Contact with hot or cold surfaces

Other Triggers

• Fracture below injury level (sometimes the first sign of a broken bone)
• Sexual activity or ejaculation
• Menstruation or uterine contractions
• Labor and delivery (severe AD — requires specialized obstetric management)
• Surgical or medical procedures below injury level without adequate anesthesia
• Heterotopic ossification
• Appendicitis or other visceral events below injury level

Symptoms to Recognize

Symptoms vary person to person. Know your own pattern. Common signs:

• Pounding, throbbing headache — the most consistent symptom; often described as the worst headache of your life during severe AD
• Flushing and sweating above the injury level — your body trying to dissipate heat and lower pressure
• Pale, cold, and goosebumped skin below the injury level — vasoconstriction
• Slow heart rate (bradycardia) — the parasympathetic response trying to counteract the pressure
• Nasal congestion
• Anxiety, sense of doom
• Blurred vision, spots
• Elevated blood pressure — measure it if you have any of the above symptoms

Some people only get the headache. Some only get flushing. Some get all of it. After your first few episodes you'll know your personal pattern. The headache is the most reliable warning sign.

Immediate Response Protocol

Act fast. Every minute of elevated BP increases stroke risk.

Step 2: Loosen everything. Remove or loosen any tight clothing, shoes, leg straps, binders, or anything that might be constricting below the injury level.

Step 3: Check your blood pressure. Everyone at T6+ risk should own a home BP cuff. Take a reading. If systolic is 150+ or 20+ mmHg above your normal baseline, you're in AD territory.

Step 4: Check and fix the bladder first.

• If you have a Foley or SPC: check for kinks in the tubing, check that the drainage bag isn't full and blocking flow, check that the catheter isn't blocked
• If you do IC: catheterize now even if it's not your scheduled time
• Use lubricant — don't cause additional irritation
• If a bladder spasm is preventing drainage, do not fight it; wait 60 seconds and try again

Step 5: If bladder is clear, check the bowel. Is your bowel program overdue? Are you constipated? If you use lidocaine gel, apply it to the rectal area before any manual check to reduce the additional stimulus. Manual removal of impacted stool during AD can worsen the episode — have someone assist if possible, and move slowly.

Step 6: Systematically check skin and other triggers. Check pressure points, check for anything pressing or tight, check your skin for injuries. Remove the cause if found.

Step 7: Monitor BP every 5 minutes. If pressure is coming down and symptoms are improving, continue working through possible causes. If pressure remains dangerously high (systolic 150+ after addressing obvious triggers), consider medication.

Medications for Acute AD

If BP remains elevated after basic trigger removal:

Nitropaste (nitroglycerin ointment) — applied to the skin above the injury level (forehead, chest, or arm). Works within minutes to lower BP. Wipe off once BP stabilizes. Caregivers must wear gloves — nitro absorbs through skin. This is the most commonly recommended acute medication for AD.

Nifedipine (Procardia) — traditionally prescribed for AD in some centers, though nitropaste has largely replaced it. If prescribed, follow your physician's instructions.

Captopril sublingual — used in some international protocols.

Keep whatever medication your SCI team has prescribed on hand at all times — in your wheelchair bag, at your bedside, in your car.

When to Call 911

Call 911 immediately if:

• You cannot identify and remove the trigger within 5–10 minutes
• Blood pressure remains dangerously elevated (>150 systolic or >40 above baseline) despite treatment
• You develop signs of stroke: sudden severe headache, facial drooping, arm weakness, slurred speech, vision changes
• You lose consciousness
• You are alone and cannot manage the episode safely

Give emergency responders your AD wallet card (see below). Many ER staff have limited experience with AD. Your card tells them exactly what to do.

Prevention

The best management is prevention. The fundamentals:

• Consistent bladder program — never let your bladder overfill; keep catheter volumes under 400–500 mL; check catheter patency regularly
• Consistent bowel program — prevent constipation and impaction; don't delay your program
• Daily skin inspection — find pressure injuries early, before they become AD triggers
• Wear properly fitting clothing and equipment — no tight waistbands, no leg straps that dig in
• Use lidocaine gel during bowel program — reduces the stimulus of digital rectal stimulation
• Know your triggers — after enough episodes you'll know what sets yours off; manage those proactively
• Prepare medical providers before procedures — any procedure below your injury level should be discussed with your SCI team; regional or local anesthesia may be needed

For people with frequent or severe AD despite good preventive practices, a physiatrist can prescribe prophylactic medications (such as terazosin or prazosin, which are alpha-blockers that reduce the severity of the sympathetic response).

Telling Your Medical Providers

One of the most dangerous situations for people with SCI is being treated by medical staff who don't recognize AD or don't know how to manage it. ER physicians, surgeons, dentists, and other providers may have never seen it.

Always tell any provider treating you below your injury level that you are at risk for AD. Ask them specifically: "What is your plan for managing autonomic dysreflexia if it occurs during this procedure?" If they don't know what that is, your SCI physiatrist should communicate with them before the procedure.

Carry a Wallet Card

Print this information, laminate it, and carry it in your wallet and wheelchair bag. Give it to any emergency provider or anyone treating you.

Frequently Asked Questions

What is the first thing to do during autonomic dysreflexia?

Sit upright immediately and loosen any tight clothing or equipment — this uses gravity to lower blood pressure. Then look for the cause, starting with the bladder, which is the most common trigger: drain it, or check the catheter for kinks or blockage.

At what spinal cord injury level is autonomic dysreflexia a risk?

Anyone with an injury at T6 or above is at risk, and the risk is greater with higher injuries. Some people with T7–T10 injuries experience it too. Incomplete injuries, including central cord syndrome, can still cause AD.

When should I call 911 for autonomic dysreflexia?

Call 911 if you cannot find and remove the trigger within 5–10 minutes, if blood pressure stays dangerously high despite treatment, if you develop signs of stroke, or if you are alone and cannot manage the episode safely.

What medication is used for acute autonomic dysreflexia?

Nitropaste (nitroglycerin ointment) applied to the skin above the injury level is the most commonly recommended acute medication; it works within minutes and is wiped off once blood pressure stabilizes. Always follow the plan set by your SCI physician.

Sources & Further Reading

This page draws on lived SCI experience and published clinical guidance, including:

• Acute Management of Autonomic Dysreflexia — Clinical Practice Guideline (Consortium for Spinal Cord Medicine / Paralyzed Veterans of America)
• Autonomic Dysreflexia factsheet — Model Systems Knowledge Translation Center (MSKTC)
• Autonomic Dysreflexia — StatPearls, NCBI Bookshelf (NIH)