Autonomic Dysreflexia: What You Should Know

Autonomic dysreflexia (AD) is a sudden, dangerous rise in blood pressure. It can happen if your spinal cord injury is at T6 or above (and sometimes as low as T8). It is your body’s alarm about a problem below your injury — most often a full bladder, a full bowel, pressure on your skin, or something tight against you. AD is not just a headache. Left untreated, it can cause a stroke, a seizure, or death (per SCIRE / PVA AD guidelines).

The good news: once you and the people who help you know the triggers and the steps, most episodes are short and easy to stop.

🚨 Red Flags — When to Seek Emergency Care

Sit up first. Then call 911 or go to the ER if:

• Your blood pressure stays high after you clear the obvious triggers (bladder, bowel, skin, tight clothing). “High” means a top number at or above 150 mmHg, or more than 20 mmHg above your normal (more than 15 mmHg in children).
• You have a severe pounding headache, blurred vision, chest pain, trouble breathing, or you feel faint.
• You have a seizure, confusion, slurred speech, or weakness on one side.
• You cannot find or fix the trigger and you feel worse.

Stay sitting up. Do not lie down — lying flat pushes your blood pressure even higher. Tell the team right away: “I have a T6 or higher spinal cord injury, and I am having autonomic dysreflexia.” Hand over your wallet card if you carry one. Some medical staff know AD by its other name, autonomic hyperreflexia. Many clinicians outside spinal cord care have never treated AD (per PVA AD guideline).

Understanding Autonomic Dysreflexia

Your injury blocks the signals that normally warn your brain about pain below your injury level. So when something irritating happens down there — a stretched bladder, hard stool, a sharp object on your skin — your body reacts on its own. Nerves below the injury squeeze blood vessels across your belly, and your blood pressure shoots up (per SCIRE AD handout).

Your brain senses the high pressure. It tries to send a calming signal back down, but your injury blocks it. So the pressure stays dangerously high until you remove the trigger. T6 is the usual cut-off, because that is where the nerves controlling those big belly vessels branch off.

Most people at risk have at least one episode — often within the first year after injury — so it pays to learn the steps early (per MSKTC AD factsheet).

Two things make AD easy to miss:

• Your normal blood pressure is often low after SCI — often around 90–110 on top. A reading of 120/95 can look fine on a chart but be a real emergency for you. This is why knowing your own normal matters so much.
• AD can happen with few or no symptoms (“silent AD”), even when your pressure is very high. This is common during bladder tests, bowel programs, and sperm retrieval (per MSKTC AD factsheet).

What Triggers It

Almost anything that would hurt if you could feel it can set off AD. Here are the common triggers, roughly in order of how often they happen:

• Bladder (the #1 cause): a full bladder, a kinked or blocked catheter, an overfull leg bag, a bladder infection, or bladder or kidney stones.
• Bowel: constipation, hard or impacted stool, gas, hemorrhoids, or an overdue bowel program.
• Skin: a starting pressure injury, an ingrown toenail, a cut, a burn, a bug bite, tight clothing or straps, or a hard object under you.
• Sexual activity: strong genital stimulation or orgasm, in any gender. A second orgasm can push pressure even higher.
• In women: period cramps, pregnancy, labor and delivery, and breastfeeding or a breast infection after birth.
• Less common: broken bones, blood clots, belly problems (like gallstones or appendicitis), surgery, and extreme heat or cold.

Daily Prevention Routine

• Follow your bladder program on schedule. Empty on time, even when you feel fine.
• Check your catheter and leg bag every morning and before each transfer. Straighten any kinks. Keep the bag below your bladder and not overfull.
• Do your bowel program on schedule, with enough fibre and fluids. Don’t let stool build up.
• Do pressure reliefs — push-ups, leans, or tilts — every 15 to 30 minutes when you sit.
• Check your skin at least twice a day. Look at your tailbone, sit bones, and heels, and anywhere a strap or shoe presses. Use a mirror or ask for help.
• Wear loose clothes. Skip tight belts, straps, and shoes that rub.
• Treat cuts, ingrown toenails, and infections early, before they grow into triggers.
• Learn your own normal blood pressure, so you can tell when a reading is high for you.
• Keep a home blood pressure monitor, and make sure you and your helpers know how to use it.
• If your bowel program or catheter routine itself sets off AD signs, tell your provider. A gentler technique, more lubricant, or numbing gel often fixes it.
• Keep a “trigger card” in your wallet or on your phone. List your usual triggers and your first three steps.

Early Warning Signs & The Drill

You may notice one or more of these signs before — or instead of — a headache:

• A pounding headache that comes on fast
• Flushing, sweating, or red blotchy skin above your injury (face, neck, shoulders)
• Goosebumps, or pale, cool skin below your injury
• A stuffy or runny nose
• Blurred vision or spots
• Feeling anxious or uneasy; a metallic taste
• A slow (or fast) heartbeat, worse spasms, or nausea

The moment you notice any of these, act:

1. Sit up straight (90 degrees), or raise the head of your bed and lower your legs. Do not lie down.
2. Loosen anything tight: binder, stockings, waistband, straps, shoes, catheter tape.
3. Check your blood pressure if you have a monitor. Keep the cuff on and re-check every 2 to 5 minutes. Write down the numbers and times.
4. Check the bladder first. Drain the bag, unkink the tubing, or catheterize now. If you have numbing (lidocaine) jelly, put it on the catheter first and give it a few minutes to work. If a catheter won’t drain, replace it. Don’t keep flushing a bladder that isn’t emptying, and never press on or tap your belly to force the bladder to empty.
5. Check the bowel next. If it is full and your pressure is settling, do a gentle check or your usual routine. Use lidocaine 2% gel first to numb the area and wait a few minutes for it to work — it keeps AD from getting worse (per PVA AD guideline). If your pressure climbs or your symptoms get worse during the check, stop. Try again once things settle.
6. Check the skin. Look for a new red spot, an ingrown toenail, or anything pressing on you, above and below your injury. Shift it or remove it.

Sit up, loosen, then check bladder, bowel, and skin — in that order. This is the standard first response (per SCIRE AD handout). Most episodes settle within minutes once the trigger is gone. If your provider prescribed a fast-acting AD medication, know exactly when and how to use it, and keep it in your kit. For many people the plan is to use it when the top number reaches 150 mmHg, then keep working on the trigger (per PVA AD guideline).

If It Keeps Coming Back or Won’t Settle

• Don’t lie flat to “rest.” Stay upright until your pressure is stable.
• Keep looking for less obvious triggers: an ingrown toenail, a hemorrhoid, a new pressure spot, a full leg bag, or a tight binder.
• Suspect a bladder infection if your urine is cloudy, smells bad, or your spasms suddenly get worse. Call your provider the same day.
• If your pressure won’t come down, or symptoms come back with no clear cause, get emergency care. Repeated or silent AD can point to bladder stones, a fracture, or a belly problem that needs a workup.
• Try to stay as calm as you can. Anxiety and panic can push blood pressure even higher.
• Do not drive yourself during an episode.

After an Episode — Watch for the Opposite Problem

Once the trigger is fixed — especially if you used a medication — your blood pressure can swing the other way and drop too low. This is called orthostatic hypotension. You may feel dizzy, weak, tired, or faint, or your vision may blur when you sit up (per SCIRE orthostatic-hypotension handout).

• Keep checking your blood pressure for about 2 hours after the episode settles.
• If you feel faint or your reading drops low, lean back and raise your legs until it recovers.
• Tell your provider about every episode, even one you fixed yourself. They may adjust your plan.

When to Call Your Doctor or Rehab Team (Non-Emergency)

• You had an episode and aren’t sure what caused it.
• Episodes are happening more often, or taking longer to settle.
• Your usual bladder or bowel routine suddenly stops working.
• You notice new skin breakdown, or a change in spasms that lines up with AD.
• You are planning surgery, a bladder procedure, pregnancy, or sperm retrieval (see below).

Special Situations

Surgery, dental work, and procedures. You may not feel pain in the area, but anesthesia should still be used to keep AD from starting during surgery or a procedure (per SCIRE AD handout). Tell every surgeon, anesthetist, and dentist about your AD risk ahead of time.

Bladder and bowel procedures (cystoscopy, urodynamics, sperm retrieval). These stretch the bladder and bowel, and often trigger AD. Ahead of time, your team may have you do a bowel program, treat any infection, and use numbing lidocaine. Your blood pressure should be watched closely, and you may be offered medication to prevent AD (per PVA AD guideline).

Sexual activity. Strong stimulation and orgasm can raise your blood pressure more than for people without SCI, and the AD may be silent. If you are prone to it, monitor your pressure, stop and follow your AD steps if symptoms start, and re-check within a few minutes. Ask your provider about prevention if this happens often. One key safety rule: if you use an erection medicine such as sildenafil (Viagra), nitrate AD medicines — like nitroglycerin paste — must not be used for one to two days afterward. The mix can drop your blood pressure to a dangerous low, so make sure your AD plan accounts for it (per PVA AD guideline).

Pregnancy, labor, and breastfeeding. If you are pregnant and at risk for AD, you need a care team that knows SCI. AD during labor can look like preeclampsia, so it must be sorted out with care. A spinal or epidural is the most reliable way to prevent AD during delivery, even if you can’t feel pain. AD can also start afterward from breastfeeding, engorgement, or a breast infection (per PVA AD guideline).

A note on “boosting.” Setting off AD on purpose to raise blood pressure for sports is dangerous. It can cause deadly spikes, it is banned in competition, and you should never do it.

Travel, Work, and Community Adaptations

• Always travel with extra catheters, a spare leg bag, gloves, lubricant, and your trigger card.
• Carry an AD emergency kit: a blood pressure cuff, gloves, lubricating and numbing jelly for a rectal check, an extra catheter, a bladder irrigation kit, and any AD medication your doctor prescribed (per PVA / Craig Hospital AD materials).
• Brief every new caregiver on your exact AD steps on day one. Don’t assume they know SCI.
• At work or school, keep a small kit in a private spot so you can check and fix triggers fast.
• On transit, plan extra time for a bladder check before the trip home.

Caregiver / Family Quick Reference

• Learn the warning signs and your person’s normal blood pressure.
• If AD starts: sit them upright (never flat), loosen tight clothing, then check bladder, bowel, and skin in that order. Check blood pressure every few minutes.
• Wear gloves and use lubricant or numbing jelly for any rectal check. Be gentle — rough handling can make AD worse.
• If you can’t find or fix the cause, or the pressure stays high, call 911. Say it is autonomic dysreflexia in a person with a high spinal cord injury.
• Keep a simple diary of episodes — the signs, the likely cause, and what fixed it — to share with the care team.

What Many People Find Helpful

Many people keep a “trigger card” in their wallet and a photo of their AD steps on their phone, so anyone helping can act fast. Learning your own normal blood pressure early — and writing it on your card — turns a confusing reading into a clear signal.

It is common to feel that providers outside SCI care don’t recognize AD. Many people find it helps to be calm but firm: name the condition, hand over the card, and say it is an emergency. If you can’t speak for yourself, a family member who knows your plan can direct your care.

People also notice patterns — sweating that clears when they roll over, a headache with every bowel program, spasms that flare before a bladder infection. Spotting the pattern is often the key to stopping the next episode.

Evidence & Sources

Synthesized from the PVA / Consortium for Spinal Cord Medicine Autonomic Dysreflexia clinical practice guideline and consumer materials (2020/2025), MSKTC factsheets, the SCIRE Community autonomic dysreflexia and orthostatic hypotension handouts, and the Craig Hospital AD factsheet (retrieved 2026-06-24), with a nugget-level evidence cross-check against these plus the UHN Spinal Cord Essentials and SIA (UK) AD factsheets (2026-08-26). See RESEARCH-SOURCES.md for complete provenance. The core clinical detail — the response drill, the “more than 20 mmHg above baseline” definition, the 150 mmHg threshold, and the special-situation guidance — is drawn from the PVA AD guideline, cross-checked with the SCIRE and Craig handouts.

Printable One-Pager Notes

• Target length for one printed page: 950 to 1200 words. This guide runs longer for completeness, so the renderer may split it across pages.
• Keep the Red Flags block and the Drill in the top half of the page.
• Use 11 to 12 pt text and generous line spacing when printing.
• The 🚨 emoji prints fine on most printers. If yours drops it, write “RED FLAGS — EMERGENCY” by hand at the top.

You are the expert on your own body. Most people at risk for AD go long stretches between serious episodes once they and their caregivers master prevention and the response steps. Keep this guide — and your AD kit — where you and anyone who helps you can reach them fast.