Pernio, more commonly called chilblains, is an inflammatory skin condition triggered by exposure to cold, damp conditions. It causes itchy, painful, swollen patches on the fingers, toes, and occasionally the ears or nose, typically appearing hours after the skin warms back up rather than during the cold exposure itself. Despite being one of the oldest recognized cold-related skin problems, pernio is still surprisingly poorly understood, and the treatments available for it have a thinner evidence base than you might expect.
What Pernio Looks and Feels Like
The classic presentation involves purple or reddish-blue patches and raised plaques on the tips and sides of the toes or fingers. These lesions are itchy, sometimes painfully so, and they can burn or throb. In a clinical description of patients with the condition, the lesions appeared as “pruritic, at times painful, purple acral patches or plaques on the fingers, toes, and nose after exposure to a cool or cold, damp environment.”1Journal of the American Academy of Dermatology. Chilblains (Perniosis) In severe cases, the skin can blister or develop small ulcers, though most episodes stay at the swollen, discolored stage.
What catches many people off guard is the timing. Pernio does not happen during the cold exposure itself. The lesions typically show up within 12 to 24 hours after the skin has been rewarmed, and they can persist for one to three weeks if left alone. This delay is what distinguishes pernio from frostbite, which damages tissue directly during freezing. Pernio occurs at temperatures well above freezing, usually in cool, damp weather rather than extreme cold.
Why Cold and Damp Conditions Cause This
The mechanism behind pernio centers on an abnormal blood vessel response. When exposed to cold, the small blood vessels in your skin constrict to conserve heat. In people who develop pernio, this constriction appears to be excessive and prolonged. Vascular testing in patients with pernio has consistently demonstrated vasospasm upon cold exposure, suggesting this exaggerated vessel tightening plays a direct role in producing the lesions.2Dermatology. Vasospasm Is a Consistent Finding in Pernio (Chilblains) and a Possible Clue to Pathogenesis Pernio has been described broadly as a vasospastic disorder affecting unprotected skin in people exposed to nonfreezing, damp cold.3PubMed. Pernio (chilblains)
A recent clinical trial added more physiological detail. Compared to people without a history of chilblains, those prone to the condition showed significantly lower skin blood flow during cold exposure, along with reduced oxygen delivery to the tissue and increased markers of tissue oxygen deprivation.4PubMed. Physiological responses of individuals with idiopathic chilblains during cold exposure and rewarming: a nonrandomized clinical trial In plain terms, the blood vessels clamp down harder and stay clamped longer, starving the surrounding tissue of oxygen. When blood flow returns during rewarming, the resulting inflammation produces the itchy, swollen patches you see on the skin.
Skin biopsies tell a complementary story. Under the microscope, pernio lesions show clusters of immune cells packed around small blood vessels, along with swelling of the vessel walls and surrounding tissue.5Journal of the American Academy of Dermatology. Chilblains (Perniosis) A study of 38 cases found that idiopathic pernio has a characteristic pattern of immune cell infiltration around the vessels in both the superficial and deeper layers of skin, along with swelling in the upper skin layer.6PubMed. Idiopathic perniosis and its mimics: a clinical and histological study of 38 cases So the problem is both vascular (the vessels overreact) and inflammatory (the immune system piles on once blood flow returns).
Who Gets Pernio
Pernio shows a clear lean toward women. In a case-control study of 69 patients, about two-thirds were female.7PubMed Central. Chilblains in Turkey: a case-control study This sex difference is consistent across most published series, though the reasons for it are not entirely clear. Hormonal factors, differences in peripheral circulation, and lower body mass may all contribute.
Body weight appears to matter. The same study found that patients with chilblains had a significantly lower body mass index than matched controls, with the average BMI of the chilblains group about two points lower.8PubMed Central. Chilblains in Turkey: a case-control study A series of five adolescent patients with pernio at a pediatric center similarly noted that all were thin, with BMIs below the 25th percentile.9PubMed. Pernio in pediatrics Less insulating body fat, particularly in the extremities, likely means the fingers and toes cool down faster and more severely.
Occupation and lifestyle habits also play a role. A systematic review and meta-analysis found that the percentage of skin affected by chilblains was higher in studies that included more outdoor workers and people in physically demanding jobs, likely because of their prolonged exposure to cold and wet conditions.10PubMed Central. Population Characteristics, Symptoms, and Risk Factors of Idiopathic Chilblains: A Systematic Review, Meta-Analysis, and Meta-Regression Living in a damp, temperate climate without central heating is a classic risk scenario, which is why pernio has historically been common in parts of the United Kingdom, northern Europe, and other maritime-influenced climates.
How Pernio Is Diagnosed
There is no single blood test or imaging study that confirms pernio. Diagnosis is clinical, meaning your doctor recognizes it from the appearance and history: itchy or painful purple patches on the fingers or toes that appeared after cold exposure, without signs of frostbite or other vascular disease. The reason lab work often gets ordered is not to prove pernio but to rule out conditions that mimic it or that can cause secondary chilblains.
In a large series of 104 patients at a major medical center, about 37% had at least one abnormal lab finding. Among those tested, cold agglutinins (proteins in the blood that clump red blood cells at low temperatures) were positive in over half. Meanwhile, cryoglobulins were negative in every patient tested. Only about 4% had an associated connective tissue disease, and 3% had an associated blood cancer.11PubMed. Clinical characteristics, etiologic associations, laboratory findings, treatment, and proposal of diagnostic criteria of pernio (chilblains) in a series of 104 patients at Mayo Clinic, 2000 to 2011 The takeaway for you: most pernio is idiopathic, meaning it happens on its own without an underlying disease. But screening bloodwork helps catch the minority of cases where chilblains are the first sign of something else, particularly lupus or, rarely, a blood-related malignancy.
One additional diagnostic tool that researchers have explored is nailfold capillaroscopy, where a special microscope is used to examine the tiny blood vessels at the base of the fingernail. In patients with pernio, these capillaries were found to be significantly wider than in healthy controls, regardless of whether the patient was in an active flare or not.12PubMed. The capillaroscopic findings in idiopathic pernio: is it a microvascular disease? The persistence of these dilated capillaries between episodes suggests that pernio involves lasting changes to the small blood vessels, not just a temporary overreaction.
Conditions That Look Like Pernio
Several other cold-related vascular conditions can mimic chilblains, and telling them apart matters because the management differs. Raynaud phenomenon causes dramatic color changes in the fingers, cycling through white (as blood supply cuts off), blue, and then red (as blood returns). Unlike pernio, Raynaud attacks come in sharp, defined episodes, often triggered not just by cold but by emotional stress. The color changes in Raynaud also tend to reverse relatively quickly once your hands are warmed.13PubMed Central. Acrocyanosis: The Flying Dutchman
Acrocyanosis produces a persistent blue discoloration of the hands and feet, but it generally does not itch or hurt and does not produce the raised, inflamed patches of pernio. Acrocyanosis tends to be symmetrical and is often accompanied by noticeable clammy sweating of the palms and soles. The skin color normalizes when you raise your hands from a hanging position to horizontal. The two conditions can coexist, and acrocyanosis is actually more common in people who also get chilblains.14PubMed Central. Acrocyanosis: The Flying Dutchman Pain, ulcers, or tissue breakdown point away from simple acrocyanosis and toward either pernio or something more serious. A review of cutaneous vascular conditions noted that being familiar with the specific features of acrocyanosis, Raynaud, pernio, and erythromelalgia helps prevent confusion among these overlapping presentations.15PubMed. Cutaneous Manifestations of Chronic Vascular Disease
COVID Toes and the Pandemic Connection
During 2020 and 2021, dermatologists worldwide reported an unusual surge of pernio-like lesions on the toes of young, otherwise healthy people, many of whom tested positive for or had recent exposure to SARS-CoV-2. The phenomenon was quickly dubbed “COVID toes.” The lesions looked nearly identical to classic chilblains, but they appeared in warmer months and in people who had no history of cold-related skin problems.
Research into the mechanism suggested several pathways through which the virus could trigger pernio-like skin changes. The SARS-CoV-2 virus enters cells through a receptor that is part of a blood pressure regulation system, and viral infection could shift that system toward increased vessel constriction and inflammation.16PubMed Central. Pernio (Chilblains), SARS-CoV-2, and COVID Toes Unified Through Cutaneous and Systemic Mechanisms The virus also appeared to trigger a strong type I interferon immune response, particularly in younger patients whose immune systems mounted a vigorous early defense. A study examining biopsy tissue from affected patients found high interferon activity and specific immune cell infiltration in every case examined. Traces of viral genetic material were found in about a quarter of the biopsied skin samples, and notably, the affected patients lacked adaptive immune defenses against the virus, suggesting their robust early immune response may have been part of what drove the skin inflammation.17iScience. Clinical features and type I interferon immune response in SARS-CoV-2 associated pernio-like lesions
The COVID toes episode was instructive because it showed that pernio is not purely a temperature-driven phenomenon. It can be triggered by anything that activates the right combination of vascular constriction and immune-mediated inflammation in the small vessels of the extremities. As the pandemic has waned, reports of COVID-associated pernio have decreased, but the condition highlighted how closely vascular function and immune activation are intertwined in producing chilblains.
When Pernio Signals an Underlying Disease
Most pernio is idiopathic, but a subset of cases is secondary to an underlying condition. Lupus is the most common culprit among immune-mediated diseases.18PubMed Central. Chilblains in immune-mediated inflammatory diseases: a review When chilblains occur alongside lupus, the skin biopsy tends to look somewhat different from idiopathic pernio: immune cells still cluster around vessels, but there is often damage to the bottom layer of the outer skin, and the pattern of immune cell distribution differs.19The American Journal of Dermatopathology. Perniosis: Clinical and Histopathological Analysis If your chilblains are unusually severe, recur in warm weather, or come with joint pain, oral ulcers, or unusual rashes elsewhere, your doctor will probably test for autoimmune conditions.
There is also a rare genetic form called familial chilblain lupus, caused by mutations in a gene called TREX1. This gene encodes an enzyme involved in breaking down stray DNA inside cells. When the enzyme does not work properly, the cell’s innate immune sensors interpret the leftover DNA as a threat, activating the same type I interferon pathway seen in COVID-associated pernio. Families with TREX1 mutations develop cold-induced chilblain lesions of varying severity, from mild discoloration to destructive ulceration, often accompanied by signs of systemic inflammation such as joint problems and abnormal blood counts.20PubMed. Familial chilblain lupus due to a novel mutation in the exonuclease III domain of 3′ repair exonuclease 1 (TREX1) Multiple families across different populations have been identified with distinct TREX1 mutations, all converging on the same interferon-driven mechanism.21PubMed Central. Heterozygous mutations in TREX1 cause familial chilblain lupus and dominant Aicardi-Goutieres syndrome22PubMed Central. Familial chilblain lupus due to a novel mutation in TREX1 associated with Aicardi-Goutières syndrome Familial chilblain lupus is extremely uncommon, but its discovery has been valuable because it revealed the interferon pathway as a key bridge between cold exposure, immune activation, and the skin lesions of pernio.
Treatment Options and Their Limits
The first-line approach to pernio is straightforward: keep warm, keep dry, do not smoke, and avoid rapid rewarming of cold extremities. Wearing insulated, moisture-wicking socks and gloves, layering clothing, and keeping indoor environments well heated are standard prevention advice. For many people with mild, seasonal episodes, these measures are enough.
When symptoms are severe or keep coming back, the most commonly tried medication is nifedipine, a calcium channel blocker that relaxes blood vessel walls. The evidence for nifedipine is genuinely mixed, though. An older randomized trial found that nifedipine at doses of 20 to 60 mg daily significantly shortened the time to clearing of existing lesions and prevented new ones from forming.23British Journal of Dermatology. The treatment of chilblains with nifedipine: the results of a pilot study, a double‐blind placebo‐controlled randomized study and a long‐term open trial But a more recent randomized trial found no significant benefit of nifedipine over placebo after six weeks of treatment for chronic chilblains.24PubMed Central. Nifedipine vs Placebo for Treatment of Chronic Chilblains: A Randomized Controlled Trial The authors of the newer trial noted that their findings directly contradicted the older work and did not support routine use of nifedipine for this condition.
A systematic review of drug treatments for idiopathic chilblains found moderate evidence supporting both nifedipine and pentoxifylline for severe or stubborn cases, while other therapies had weaker or nonsignificant results.25PubMed Central. Pharmacologic Treatment of Idiopathic Chilblains (Pernio): A Systematic Review Pentoxifylline, a drug that improves blood flow by reducing blood viscosity, performed well in a placebo-controlled trial where treated patients showed significantly better responses at multiple time points during the study period.26PubMed. Treatment of primary perniosis with oral pentoxifylline (a double-blind placebo-controlled randomized therapeutic trial) Corticosteroid creams are sometimes used to manage inflammation, though their effectiveness in randomized trials remains debated.27PubMed. An Evidence-Based Review of Perniosis (Chilblains): Therapeutic Strategies and Integration With Raynaud’s Syndrome Management
The honest picture is that pernio treatment has not advanced as much as you would hope. The condition is not life-threatening, it often resolves on its own within weeks, and it has historically been considered too minor to attract large research investments. The result is a handful of small trials with conflicting findings, and clinicians often relying on experience as much as evidence. If nifedipine does not work for you, pentoxifylline is a reasonable next step, but the reality is that some people go through multiple treatments without finding one that reliably prevents flares.
Pernio in Children and Adolescents
Although pernio is often thought of as a condition affecting young women, it shows up in children and teenagers as well, and it can cause real alarm because the purple, swollen toes resemble more serious vascular problems. In a pediatric case series, all five patients were adolescent girls who were thin, had unremarkable blood work including negative autoimmune markers, and recovered with conservative treatment.28PubMed. Pernio in pediatrics The key reassurance for parents is that pernio in an otherwise healthy child with normal lab results is almost always a benign nuisance rather than a sign of something dangerous. That said, any child with recurrent or unusually severe lesions deserves at least a basic blood workup to rule out autoimmune conditions, since chilblain lupus can present in childhood.
Vitamin D, Home Remedies, and What Does Not Work
You will occasionally see vitamin D supplementation suggested for pernio, often based on the reasoning that people who get chilblains tend to have lower sun exposure during the winter months when the condition flares. A placebo-controlled trial tested this directly and found no difference between vitamin D3 and placebo: both groups saw the same modest improvement in symptoms over the study period.29International Journal of Dermatology. An Evidence-Based Review of Perniosis (Chilblains): Therapeutic Strategies and Integration With Raynaud’s Syndrome Management This does not mean vitamin D is worthless for general health, but it does not appear to help chilblains specifically.
Traditional home remedies for chilblains are plentiful and range from rubbing the affected skin with onion slices to soaking feet in warm turnip water. None of these has been tested in controlled trials. One thing that is clearly counterproductive is rapid warming, such as holding cold feet directly against a radiator or plunging them into hot water. The sudden rush of blood into constricted vessels seems to worsen the inflammatory reaction. Gradual rewarming is safer and more comfortable.
Smoking deserves a specific mention. Nicotine constricts blood vessels, and smokers who are prone to pernio tend to have more frequent and more severe episodes. Quitting or at least reducing smoking is one of the few lifestyle changes with a clear physiological rationale for helping. Similarly, tight footwear that compresses the toes and restricts circulation should be avoided during cold months if you are susceptible.
Lasting Microvascular Changes
One underappreciated aspect of pernio is that it may not be a purely episodic condition for everyone. The capillaroscopy findings mentioned earlier, showing persistently widened capillaries even between flares, suggest that the small blood vessels undergo structural changes over time.30PubMed. The capillaroscopic findings in idiopathic pernio: is it a microvascular disease? Whether these changes are a consequence of repeated bouts of pernio or a pre-existing vulnerability that makes certain people prone to the condition in the first place remains an open question. The finding that people with a history of chilblains show heightened vasoconstriction and tissue oxygen deprivation during cold exposure, even when they are not actively flaring, supports the idea that susceptibility has a structural component.31PubMed. Physiological responses of individuals with idiopathic chilblains during cold exposure and rewarming: a nonrandomized clinical trial For people with recurrent pernio, this may explain why the condition does not simply go away after one bad winter. The underlying vascular trait persists, waiting for the next season of cold, damp weather to produce another round of lesions.