What this article will and will not do
This is a physiology publication for people who are outdoors in cold weather by choice. Cold does several things to skin, and some of those things have names in medicine.
We are going to describe the recognised phenomena at the level of what is happening and what it looks like, so that you can tell the difference between the normal response you should expect and something you should get looked at. We are not going to tell you which one applies to you, we are not going to suggest treatment, and we are not going to describe how any of these is managed.
The organisations to go to are the ones we cite throughout this site: a pharmacist first for most things, a GP where a pharmacist says so or where something recurs, and the British Association of Dermatologists for patient information written by dermatologists.
The ordinary responses
Reduced surface blood flow. In the cold, blood vessels near the skin surface narrow so that less warm blood is brought to a surface that will lose heat. Skin becomes paler and colder, most obviously at the extremities. This is the body doing exactly what it should.
Reactive flushing on rewarming. When you come back into the warm, surface blood flow increases, often overshooting. Skin becomes red, hot and sometimes prickly or itchy. For most people this is unremarkable and settles.
Stiffness and reduced dexterity. Cold tissue is less pliable. Cold skin is stiffer, cold tendons move less freely and fine control degrades. From a barrier point of view, stiff skin is skin that cracks rather than bends.
Cold induced sweating oddities and post exposure itch. Many people notice itching on rewarming. In ordinary cases this accompanies the reactive increase in blood flow and settles as the skin warms.
Recognised entities, described only
The following are recognised clinical entities. We describe them so you can recognise that what you are seeing might be one of them and take it to someone qualified.
Cold urticaria. A form of urticaria in which weals, that is raised itchy swellings, appear on skin that has been exposed to cold, typically appearing during rewarming rather than during the exposure itself. Reactions can involve larger areas of skin. In some people, extensive cold exposure such as immersion has been associated with severe systemic reactions. This is precisely why we will not treat it as a curiosity: anyone who develops weals after cold exposure, and particularly anyone who swims or surfs in cold water, should get it assessed properly rather than read about it. If cold exposure has ever been followed by faintness, breathing difficulty, swelling of the lips, tongue or throat, or collapse, that is emergency territory and the number is 999.
Chilblains, also called perniosis. Small itchy or painful red or purple swellings, classically on toes and fingers, appearing hours after exposure to cold and damp conditions that are not freezing. Common in Britain for obvious reasons. Recognised, described in NHS material, and worth showing to a pharmacist or GP rather than self managing indefinitely.
Cold induced colour change in fingers and toes. Episodes in which digits change colour on cold exposure, sometimes in stages, often with pain or numbness and discomfort on rewarming. This has recognised causes and it is a reason to see a GP, particularly if it is new, one sided, severe or affecting your ability to work.
Non freezing cold injury. A recognised injury from prolonged exposure of the extremities to cold and wet conditions above freezing. It is a serious matter with occupational relevance, and it is emphatically not something to manage from a website.
Frostbite. Freezing injury to tissue. It requires urgent medical attention. We mention it only to be complete.
How to tell the difference at the level you can
You cannot diagnose from a table and we are not offering one. What you can do is notice whether something is inside the ordinary pattern or outside it.
Inside the ordinary pattern: pale cold skin during exposure, redness and warmth for a while afterwards, general stiffness, dryness that responds to reduced load, and everything settling within a few hours of getting warm.
Outside it: raised itchy weals, swelling, blistering, skin that stays discoloured, pain out of proportion, numbness that persists, anything affecting one digit and not the others, anything that follows a pattern of getting worse each time, and any systemic symptom at all.
That is the whole of the judgement we think a publication should offer. The second list is a list of reasons to be seen, not a list of things to look up.
| Inside the ordinary pattern | Reasons to get assessed |
|---|---|
| Pale, cold skin during exposure | Raised itchy weals after cold exposure |
| Redness and warmth for a while on rewarming | Swelling, blistering or broken skin |
| General stiffness and reduced dexterity | Colour change that persists after rewarming |
| Dryness that responds to reduced load | Pain or numbness out of proportion, or that persists |
| Everything settling within a few hours | Anything affecting one digit and not the others |
| No systemic symptoms whatsoever | Any faintness, breathing difficulty or swelling beyond the exposed area |
Ordering framework written by this publication from general skin physiology. It is not a measurement, it is not taken from any study, and no number in it is a reading.
Why this matters more for cold water than for cold air
There is one thing specific to our readership worth stating plainly. Cold water immersion is a much more intense cold exposure than cold air, applied to a large area of skin at once, and it carries its own set of risks that are nothing to do with the barrier. The RNLI publishes clear public safety material on cold water shock and on what to do in the water, and it is better than anything we could write.
For skin specifically, the relevance is that a person with a cold triggered skin response may encounter a far larger dose in the sea than they ever would on land. That is a reason to have any suspected cold triggered reaction assessed before the next winter, rather than after an incident.
The line
Everything else on this site is about the physics of a structure and the loads applied to it. This article exists to mark the boundary of that approach.
Dry, tight, rough, flaking and split skin in cold conditions is what we describe. Weals, swelling, persistent colour change, blistering, discharge, spreading and anything systemic are not, and no amount of reading about barrier physiology substitutes for being looked at.