Part of Carpal tunnel syndrome
What causes carpal tunnel to flare up, and why it is in both hands
Warning signs, and when to get help
What causes carpal tunnel to flare up?
What causes carpal tunnel to flare up, in most hands, is how the wrist has been held and how hard it has been working. The tunnel is a fixed space on the palm side of the wrist with the nerve and the finger tendons sharing it, so anything that crowds it further shows up as tingling, numbness or ache in the thumb, index, middle and ring fingers.
There is a measurement behind that, and it is old but it is the kind of study that settles an argument. Gelberman and colleagues put a fine catheter into the tunnel in 15 people who had carpal tunnel syndrome and in 12 people who did not, and read the pressure inside. With the wrist straight it was 32 mmHg in the affected group against 2.5 in the others. Bend the wrist forward to 90 degrees and it went to 94 against 31. Bend it back 90 degrees and it reached 110 against 30 (Gelberman and colleagues, 1981).
Those were end-range positions held in a laboratory by a small number of people, and 90 degrees of bending back is further than most wrists go on their own, so the numbers are not a prediction about your own wrist. The pattern is the useful part: a tunnel that is already crowded reacts to position far more steeply than a roomy one does. That is why ten minutes of something a colleague does all day without noticing can leave your hand buzzing.
So the ordinary triggers are the ones you would guess, and they share a mechanism:
- A wrist held in one position for a long stretch. OrthoInfo gives holding a phone, driving and reading a book as everyday examples of how symptoms get going.
- Gripping hard, especially with the wrist bent at the same time. The NHS names work or hobbies with repeated wrist bending or hard gripping, such as using vibrating tools, among the things that make this condition more likely in the first place.
- A change rather than an amount. A fortnight of painting, a house move, a new baby, a different mouse, a borrowed keyboard at a worse height. Hands tolerate what they are used to.
- Sleep, which has a section of its own below.
A few popular triggers need dealing with straight. Stress, the weather and food are all common search terms and we have no source worth citing on any of them, so this page does not list them as causes. Typing is the other one. It is the trigger readers name most often, and it is not on the NHS list of what makes carpal tunnel syndrome more likely, which names repeated wrist bending and hard gripping instead. If your symptoms do start at a desk, the setup worth changing is covered in wrist pain from typing and desk work, and the program itself sits on the main carpal tunnel syndrome page.
Before the detail, one honest caveat. Not every flare has a trigger you can find. The NHS describes symptoms that often start slowly and come and go, so a week that is worse for no reason you can name is still inside the usual behavior of this condition. Spend ten minutes looking for the cause, not three days.
Why it flares at night and when you lie down
Position again, with nobody at the controls. Asleep, the wrist curls up and stays curled, and the first thing that tells you is the tingling that wakes you. Lying on your side with the hand tucked under the pillow or under your own body does the same thing. The NHS says symptoms are usually worse at night, and most people with this condition find that out before they find out what it is called.
Why the night behaves this way, where to put the arm in bed, and what to do at 3am when you are already awake are all on how to sleep with carpal tunnel. What shaking and flicking the hand is doing, and which symptoms settle first as things improve, sit under "Why it wakes you, and what settles first" on the main carpal tunnel syndrome page. Neither gets repeated here.
Why did it flare up suddenly?
Most sudden flares are not sudden on inspection. Look at the two days before it started and there is usually a long drive, a day of hard graft, a wrist held bent for an evening, or a night in an awkward position. Working backward like that is worth the effort, because a trigger you can name is a trigger you can take away.
Four sudden patterns are not flares at all, and they go in a different direction.
A hand that went numb or tingly after a fall or a blow to the wrist. That is an emergency route, not a management question, and the first two warning signs below give the wording.
There is a reason it is treated that quickly. Bauman and colleagues described five people in whom pressure in the tunnel built up acutely, four of them after a wrist fracture, and four were operated on between 36 and 96 hours after the injury, with only one showing an early return of nerve function (Bauman and colleagues, 1981). That is a tiny series from 1981 and not a prediction, but the direction is clear enough: numbness after a wrist injury is looked at today, not next week. Recovery after a broken wrist, including what to expect from the cast weeks, is on wrist fracture rehab.
Sudden weakness or numbness down one side, a drooping face, muddled speech or a sudden loss of vision. That is the first warning sign below, and it is emergency services, even if it passes off.
A hand or arm that turns cold, pale, blue or gray compared with the other side. That is the blood supply to the arm rather than the nerve in the wrist, and it is on the warning list below as an emergency.
Numbness that has arrived and simply stayed, or a thumb that has become weak over a few weeks. That is the condition progressing rather than flaring, and it has its own section further down.
How long does a flare-up last?
There is no published figure for this, and inventing one would be worse than leaving the gap open. What can be given is what the length depends on.
Whether the trigger is still going. A flare caused by a job you have finished behaves very differently from one caused by the way you hold your work all day.
Whether the tingling still comes and goes, or has become constant. Intermittent tingling that quiets within days of taking the load off is the usual pattern. Numbness that no longer lifts at all is not a long flare and should not be waited out.
How long you have had it. OrthoInfo says carpal tunnel syndrome gets worse over time in most people, with symptoms becoming more frequent or lasting longer, so a hand that has been going for two years will not behave like a hand that started last month.
Then there is the point where waiting stops being reasonable, which is what the question is usually really asking. The NHS says to see a doctor if your symptoms are getting worse or are not going away, or if treatment at home is not working. If the numbness is there all the time, the thumb is weakening, or the muscle at the base of the thumb looks flatter than on the other side, the last warning sign below asks for a doctor within a few days rather than a wait and see, and that time frame exists because long-standing nerve compression can leave damage that does not come back.
What to do during a flare-up
Nothing here is new treatment. It is the same first steps the condition already has, used harder for a week or two, and it sends you back to the main carpal tunnel page for the detail instead of building a second version of it.
Take the load off the part of the day that caused it. The NHS advice is to stop or cut down on anything that has you bending the wrist often or gripping hard. For a flare that usually means one or two specific tasks, not resting the hand, and a hand that stops being used altogether gets stiff and weak without the nerve getting any happier. Which tasks and which exercises are the likely ones, sorted by what they ask of the wrist rather than by name, is on carpal tunnel exercises to avoid, so this page does not list them again.
Use the night splint, if you have one. Most readers will have bought theirs as a wrist brace; either way the job it does is to keep the wrist from curling while you sleep. How well splints work, how long the NHS expects you to wear one before it helps, and how to check that yours holds the wrist close to straight rather than bent back are all on the main carpal tunnel syndrome page, with the evidence attached.
Keep the gentle movement going, smaller than usual. The median nerve glide and tendon glides are the two that most programs use, and during a flare the thing that governs them is the response, not the repetition count. After carpal tunnel surgery, a wrist fracture or any other hand surgery, check with your surgeon or hand therapist before you restart nerve glides.
During the glides, aim for no tingling. If a faint tingle comes on, make the movement smaller; it should settle within a few seconds of stopping. Tingling or numbness that builds with each repetition, lasts after you stop, or makes your night symptoms worse means the exercise is too much. Leave it out or drop back a stage. There is no separate reduced flare dose on this site, because none of the sources gives one. The doses on the main carpal tunnel page are the doses, and your physio or physical therapist will adjust this to your hand. The rule for moving between stages is there as well.
Some people find self-massage for carpal tunnel comfortable alongside the glides. Treat that as a comfort measure, not as treatment for the nerve.
Judge the next day rather than the next minute. A task that leaves your hand buzzing for twenty minutes is different from one that leaves your night worse, and the pain monitoring model is the general way of making that call.
On painkillers, the NHS position is worth knowing: paracetamol or ibuprofen may help the pain short term, but there is little evidence they treat the cause, so they are not the plan. Ask a pharmacist whether either suits you and what else you take.
Why do you get carpal tunnel in both hands?
Because almost nothing that causes it is one-sided. The shape and size of your own tunnel, which OrthoInfo describes as likely to run in families, is the same on both wrists. Body-wide conditions do not pick a hand. Pregnancy, body weight and the hormonal changes OrthoInfo names do not either. Even the work: most two-handed jobs load both wrists, just not equally. Pregnancy has a page of its own, because both the explanation and what happens later are different: carpal tunnel in pregnancy and after the birth covers why both hands are the usual pattern then, and what the follow-up studies found after the birth.
Two studies have put numbers on it. Both come from hospital clinics and not from the general public, and that is the thing to hold on to while you read them. Padua and colleagues followed 133 people with carpal tunnel syndrome, 266 hands, and found clinical symptoms in both hands in 87%. About half of the hands with no symptoms at all still showed median nerve impairment on nerve testing, most of the people who started with one-sided symptoms went on to get them on the other side, and whether both hands were involved was related to how long symptoms had been going on rather than to how severe they were (Padua and colleagues, 1998).
Bagatur and Zorer reviewed 131 people, 229 hands, who had surgery for it: symptoms were on both sides in 59% at first presentation, 66% of the symptom-free hands had abnormal nerve testing, and their conclusion was that this is a bilateral condition that becomes more obvious with time (Bagatur and Zorer, 2001).
Those numbers describe a condition. They are not a forecast for your second hand. People who reach a hospital clinic or an operating list have had this longer and worse than average, so the percentages run high. What they do settle is the question readers come with: no, two hands is not strange, and no, it does not mean you have done something unusual to both wrists.
It does change one practical thing. Two hands at once is a reason to mention the rest of your health, not a reason to treat the wrists as two separate jobs. The NHS names arthritis and diabetes among the conditions that make carpal tunnel syndrome more likely, and OrthoInfo names diabetes, rheumatoid arthritis and thyroid imbalance as conditions associated with it.
None of that means you have any of them, and this page cannot tell you whether you do. What it means is that the person assessing you should hear about both hands, your general health and the medicines you take. Inflammatory joint disease has its own page at rheumatoid arthritis. The wear-and-tear kind can crowd a wrist too, and it is a common companion in older hands: hand osteoarthritis is the page for that.
When both hands means something else
Both hands is usually ordinary, as the section above says. It is also the pattern one serious alternative produces, so both things get said, in that order.
Numbness or tingling in both hands along with hands that have slowly become clumsy, dropping things, fumbling buttons, struggling with keys, can come from pressure on the spinal cord in the neck rather than from the wrists. The warning sign below carries the full wording and asks for medical advice the same day, with emergency services if the clumsiness or numbness is getting worse quickly.
This is not a rare academic point. Davies and colleagues, writing on degenerative cervical myelopathy, say that in their clinical experience a diagnosis of carpal tunnel syndrome is often wrong when it is made on both sides, and that the cord problem usually accounts for the hand symptoms in those patients (Davies and colleagues, 2018). That is the judgment of a specialist team rather than a measured rate, and they report it as such. The features they list alongside the hands are the ones to take notice of: loss of dexterity, unsteadiness, altered walking, falls, and bladder or bowel changes. New problems with walking or with your bladder or bowels, or hands that have become clumsy suddenly, are the emergency line below.
It helps to know the other two explanations, so you can see where your own pattern fits. A nerve root pinched in the neck usually gives one arm, often with neck or shoulder blade pain and a band of symptoms running down to particular fingers, and that is cervical radiculopathy; the neck itself is covered in neck pain. Numbness and burning in both hands and both feet points somewhere else again, toward a widespread nerve problem and not a trapped one, and that is peripheral neuropathy.
Nobody sorts this out from a web page, including this one. Which of them you have is settled by an assessment, and the point of this section is only to tell you which patterns deserve to be mentioned rather than put up with.
Flare-up or getting worse? How to tell the difference
This is the distinction that matters most on the page, because the two need opposite responses: a flare needs the load taken off for a week or two, and progression needs an appointment.
A flare is the same symptoms, louder, in the same fingers, and it moves. It comes on after something, it eases when that something stops, and between flares the hand goes back to how it was. Tingling that comes and goes is the condition's normal behavior, and that is how the NHS describes it.
Progression is quieter and it does not move. The numbness stops lifting and is simply there, morning and evening. The thumb starts to feel weak or clumsy rather than sore, you drop more than you used to, and the fleshy pad at the base of the thumb can look flatter or thinner than on the other hand. OrthoInfo says this condition gets worse over time in most people, that symptoms become more frequent or last longer, that the thumb muscles can become visibly smaller in severe cases, and that surgery may be recommended for long-standing cases with constant numbness and wasting of the thumb muscles to head off damage that cannot be undone. How that decision is reached, and the evidence behind it, is in the surgery section of the main carpal tunnel syndrome page.
There are two questions you can ask yourself at home, and neither of them diagnoses anything. First, what is the hand like on your quietest day, not your worst? A hand that is back to normal on a rest day is flaring. A hand that is numb on a rest day is not. Second, compare this month with three months ago instead of this week with last week, because that is the timescale progression works on and the timescale a flare hides inside.
When a flare needs an appointment, and how quickly
The warning signs below are sorted by how fast to act and carry the exact wording for each, so this is the short version of where a flare fits.
Straight to emergency services or an emergency department: any sign of a stroke, even a brief one, a hand that has gone numb or changed shape after a fall or an injury to the wrist, and a hand or arm that turns cold, pale, blue or gray compared with the other side. Also the cord lines below, which are new trouble walking, new bladder or bowel trouble, or hands that have become clumsy suddenly.
The same day: numbness or tingling in both hands with hands that have slowly become clumsy. A wrist injury that has left the wrist swollen, bruised or unusable even without numbness. An electric shock feeling down the back or into the limbs when you bend your head forward. And thumb weakness that is getting worse day by day or spreading past the thumb.
Within a few days: numbness that is there all the time, a thumb that is getting weaker, or a flatter muscle at the base of the thumb.
Otherwise, and this covers most flares, the NHS route applies: see a doctor if your symptoms are getting worse or not going away, or if what you are doing at home is not working. In parts of the UK you can refer yourself to community musculoskeletal services for physiotherapy, which the NHS page mentions. In the United States that assessment usually comes from a physical therapist or a PT; elsewhere from a physio. If you are offered a hand therapist, take it, because hands are what they do all day.
If you keep two sentences from this page, keep these. A flare is usually the same problem under more load, and it answers to taking the load off. A hand that is numb all the time, a weakening thumb, or two clumsy hands is not a flare and does not answer to anything you can do at home, which is exactly why those three have a time frame attached instead of advice.
Related exercise programs
Warning signs
Get emergency help now
- Emergency: any sign of a stroke, even if it goes away. That means a face that droops on one side, an arm you cannot lift or keep up, slurred or muddled speech, weakness or numbness on one side of your body or face, sudden blurred vision, double vision or loss of sight, trouble swallowing, sudden dizziness with unsteadiness or falling over, a sudden severe headache, or a sudden fall where your legs give way but you do not black out (a drop attack). Call emergency services straight away.
- Emergency: numbness, tingling or pins and needles in the hand after a fall or injury to the wrist, or a wrist that has changed shape or sits at an odd angle. The same applies to a bone showing through the skin or a cut that is bleeding heavily. Go to an emergency department or call emergency services straight away, and do not drive yourself. The wrist may be broken.
- Emergency: your arm, hand or fingers turn cold, pale, blue or gray compared with the other side. Call emergency services or go to an emergency department straight away, and do not drive yourself. The blood supply to the arm may be blocked.
- Emergency: new problems walking, for example your legs feel stiff, heavy or weak or you have become unsteady on your feet, new trouble controlling your bladder or bowels, or hands that suddenly become clumsy, for example you can no longer do up buttons. Call emergency services straight away. These can be signs of pressure on the spinal cord in the neck.
Get help today
- A wrist injury that has left the wrist swollen, bruised or so painful you cannot use the hand, without numbness or a change in shape. Get medical advice the same day.
- Numbness or tingling in both hands together with hands that have slowly become clumsy, for example trouble doing up buttons or dropping things. Get medical advice the same day. These can be signs of pressure on the spinal cord in the neck (cervical myelopathy) rather than a problem at the wrist. If the clumsiness or numbness gets worse quickly, call emergency services straight away.
- An electric shock feeling runs down your back or into your arms or legs as your head bends forward. Stop and get medical advice the same day.
- Pins and needles in an arm together with neck or arm pain, or an arm that feels heavy or weak, and nobody has checked it yet. Get medical advice the same day.
Book an appointment
- Numbness in the hand that is there all the time, the fleshy muscle at the base of your thumb looks flatter or thinner than on the other hand, or your thumb is getting weaker and you keep dropping things. See a doctor within a few days rather than waiting for it to settle. If the weakness is getting worse from day to day or spreads beyond the thumb, get medical advice the same day. In long-standing cases the nerve can be damaged for good, and surgery may be recommended to prevent that.
Common questions
Can stress cause carpal tunnel to flare up?
We have no source that tests it, so this page will not tell you that it does or that it does not. What can be said honestly is what a stressful week usually contains: longer hours, more typing, more driving, a tighter grip on everything, worse sleep and fewer breaks. Every one of those is a load on the wrist, and load is what the measured evidence points to (Gelberman and colleagues, 1981). In the clinic, when someone says a flare came out of a stressful fortnight, we can almost always find the extra hours or the extra gripping inside it, which is practice experience rather than a published finding. It also matters because the hours are something you can change and the stress often is not.
Why does my carpal tunnel flare up when I lie down?
Because of what the wrist does once you stop paying attention to it. Asleep or lying reading, the wrist tends to curl, and nothing wakes you to straighten it until the hand is already tingling. The NHS describes symptoms that come and go and are usually worse at night, so being woken by it fits the condition and does not signal a new problem. Why the night is the loudest part of this condition, and what to do when you are already awake at three in the morning, is on how to sleep with carpal tunnel.
Can you get carpal tunnel in both hands at the same time?
Yes, and in hospital series it is the usual picture, not the exception. Padua and colleagues studied 133 people with carpal tunnel syndrome, 266 hands in total, and found symptoms in both hands in 87% of them, with nerve impairment showing on testing in about half of the hands that had no symptoms at all (Padua and colleagues, 1998). Bagatur and Zorer reviewed 131 people who went on to have surgery and found symptoms on both sides in 59% at the point they first came in (Bagatur and Zorer, 2001). Both of those figures come from people who had reached a hospital clinic, so they run higher than they would across everyone who ever gets this, and neither tells you what will happen to your own second hand.
Is carpal tunnel in both hands worse than in one?
Not automatically, and the honest answer has two halves. Having it in both hands does not mean the nerve is more badly squeezed in either one, and severity is judged hand by hand, on what each hand can feel and do. The practical difference is that two hands leave you no spare hand, so the same level of symptoms costs you more at work and at home. The other half is the one worth acting on: numbness in both hands alongside hands that have slowly become clumsy is on the warning list below, because that pattern can come from the spinal cord in the neck rather than from either wrist, and it needs medical advice the same day.
Should I stop my exercises during a flare?
Usually they are made smaller, not stopped, and the rule is the same one the main program uses. During the glides, aim for no tingling. If a faint tingle comes on, make the movement smaller; it should settle within a few seconds of stopping. Tingling or numbness that builds with each repetition, lasts after you stop, or makes your night symptoms worse means the exercise is too much. Leave it out or drop back a stage. There is no separate reduced flare dose on this site, because none of the sources gives one. The doses on the main carpal tunnel page are the doses, and your physio or physical therapist will adjust this to your hand.
References
- NHS. Carpal tunnel syndrome. Page last reviewed 17 April 2024. https://www.nhs.uk/conditions/carpal-tunnel-syndrome/
- American Academy of Orthopaedic Surgeons. Carpal tunnel syndrome. OrthoInfo. https://www.orthoinfo.org/en/diseases--conditions/carpal-tunnel-syndrome/
- Gelberman RH, Hergenroeder PT, Hargens AR, Lundborg GN, Akeson WH. The carpal tunnel syndrome. A study of carpal canal pressures. Journal of Bone and Joint Surgery (American volume). 1981;63(3):380-383. https://pubmed.ncbi.nlm.nih.gov/7204435/
- Padua L, Padua R, Nazzaro M, Tonali P. Incidence of bilateral symptoms in carpal tunnel syndrome. Journal of Hand Surgery (British and European Volume). 1998;23(5):603-606. https://doi.org/10.1016/s0266-7681(98)80010-7
- Bagatur AE, Zorer G. The carpal tunnel syndrome is a bilateral disorder. Journal of Bone and Joint Surgery (British Volume). 2001;83(5):655-658. https://doi.org/10.1302/0301-620x.83b5.11350
- Bauman TD, Gelberman RH, Mubarak SJ, Garfin SR. The acute carpal tunnel syndrome. Clinical Orthopaedics and Related Research. 1981;(156):151-156. https://pubmed.ncbi.nlm.nih.gov/7226645/
- Davies BM, Mowforth OD, Smith EK, Kotter MR. Degenerative cervical myelopathy. BMJ. 2018;360:k186. https://doi.org/10.1136/bmj.k186
Written and checked by the PocketPhysio editorial team. Last updated 2026-10-17.
This page is general education, not a diagnosis or a personal treatment plan. See a physiotherapist or doctor for advice about your own situation.