Everything you need to know about cold-induced skin allergy.

Cold urticaria, often referred to as cold allergy, is a specific form of urticaria triggered by cold exposure, without any allergen being involved. This is why the term cold allergy, although frequently used, is actually incorrect. The areas most affected are typically those most exposed, such as the hands and face. Clinically, this condition is classified among the chronic inducible urticarias.

Cold urticaria can present a medical challenge, as some atypical forms may progress to severe reactions such as cold-induced anaphylaxis.

Although advances have been made in understanding and managing cold urticaria, many questions remain. The average duration of the condition spans several years, and its clinical presentation can vary, making personalised diagnosis and treatment sometimes complex.

The symptoms of cold urticaria appear rapidly after exposure to cold, often within minutes.

They manifest as the appearance of red, swollen patches, sometimes accompanied by oedema, on the areas directly exposed: hands in contact with a cold object, the face, the soles of the feet on a cold surface, or following ingestion of cold foods or beverages. These lesions are typically intensely pruritic and may be accompanied by burning or tingling sensations. They resolve spontaneously once exposure ceases, within a few minutes to a few hours.

In some individuals, cold urticaria may be accompanied by more general symptoms, reflecting a systemic reaction. Headaches, a feeling of malaise, fever, joint or abdominal pain can then occur. In more severe cases, respiratory discomfort, swelling of the lips or throat, or even an anaphylactic reaction may develop, particularly during significant exposures such as cold-water swimming. Although these situations are rare, they warrant particular vigilance and immediate medical attention.

Often confused with each other and both influenced by low temperatures, cold urticaria and eczema are nonetheless two distinct conditions.

In summary, cold urticaria is an acute and transient reaction directly triggered by cold, whereas eczema is a chronic disorder whose symptoms can be exacerbated by winter conditions.

The exact causes of cold urticaria remain poorly understood.

However, several mechanisms are suspected. The main hypotheses include autoimmunity, auto-allergy and abnormalities in skin temperature detection. Exposure to cold could trigger the formation of novel autoantigens, leading in sensitised individuals to an immunoglobulin E (IgE)-dependent mast cell activation, which manifests as urticarial wheals.

Some studies have highlighted the presence of autoantibodies directed against IgE or mast cell receptors in certain patients, suggesting a possible role for type IIb autoimmunity. In some cases, circulating histamine-releasing factors may also contribute to skin reactions independently of IgE. Moreover, mast cells—immune cells—participate in the development of the allergic response. Their rapid degranulation upon cold exposure triggers the release of histamine and other inflammatory mediators, such as prostaglandins and TNF-α.

Moreover, cold-sensitive TRP ion channels (TRPM8 and TRPA1) appear to be involved in the cutaneous detection of cold and in the modulation of inflammatory responses. Other factors, such as the potential presence of cryoglobulins or abnormalities in the enzymatic regulation of mast cells, could play a secondary role in the pathophysiology of the disease.

Finally, there is a familial hereditary form of cold urticaria. This is a genetic autosomal dominant condition that is present throughout the individual’s life. This particular mode of transmission means that the mutation is located on a non-sex chromosome and that only a single copy of the gene needs to be affected for the disease to develop. This form of cold allergy is very rare and is thought to be linked to the intestinal microbiota.

Cold urticaria may manifest suddenly in an otherwise healthy individual, then disappear without explanation a few years later. Young adults and women appear to be more commonly affected.

The diagnosis of cold urticaria is primarily based on the clinical history, which enables clear identification of a relationship between cold exposure and the rapid onset of urticarial wheals.

To confirm the diagnosis and assess its severity, cold provocation tests are generally carried out in a clinical setting. The simplest and most commonly used is the ice cube test. It involves applying an ice cube, wrapped in a plastic bag or placed in a medical glove, to the inner forearm for about five minutes. After removing the ice cube, the skin is observed approximately ten minutes later: the appearance of a localised urticarial wheal is considered a positive result. This test confirms cold sensitivity but does not precisely indicate the temperature threshold that triggers the reaction.

For a more precise evaluation, especially in atypical or severe cases, a standardised device such as the TempTestcan be employed. This apparatus applies various controlled temperatures to the skin of the forearm, enabling accurate determination of the minimum temperature capable of triggering an allergic reaction.

In certain cases, blood tests may also be prescribed. They do not permit a direct diagnosis of cold urticaria, but can be useful for investigating associated causes or immunological abnormalities, particularly in secondary forms or when symptoms are unusual.

These tests must always be performed under medical supervision. It is strongly discouraged to attempt to replicate an ice cube test yourself, as unmonitored cold exposure can trigger a significant or even systemic reaction in some individuals.

First and foremost, the management of cold urticaria relies on prevention and avoidance of the triggering factor, namely exposure to cold.

On a daily basis, this involves protective measures. It is, for example, recommended to wear warm clothing in winter (gloves, scarf, woolly hat), to avoid direct contact with cold objects, to be wary of icy beverages or foods, and to refrain from swimming in cold water (unheated pool, lake, sea).

From a medical perspective, treatment primarily relies on the administration of antihistamines orally, prescribed by the doctor. These drugs block the action of histamine, the key mediator in urticaria, and are generally effective at preventing the onset of wheals or reducing their severity. The dosage and duration of antihistamine therapy are adjusted according to symptom severity and frequency. In more severe presentations, particularly if an episode of cold-induced anaphylaxis has already been documented, a adrenaline auto-injector may be prescribed prophylactically. It should be used as an emergency measure in the event of a severe systemic reaction.

In severe cases or those resistant to conventional treatments, more targeted therapeutic options can be considered. A clinical study thus described the case of an adolescent presenting with cold urticaria whose symptoms gradually worsened over two years, despite treatment with H1 antihistamines and leukotriene antagonists. The reactions, initially cutaneous, became systemic during immersion in cold water, particularly in a marine environment. The introduction of anti-IgE therapy led to the complete resolution of clinical manifestations.

This marked improvement supports the hypothesis of a central role for IgE and its high-affinity receptor (FcεRI) in cold-induced mast cell activation. By reducing free IgE levels, this type of treatment could limit mast cell degranulation and the release of mediators responsible for the symptoms of cold urticaria. Although this finding is based on a single clinical case, it opens up interesting prospects for the management of severe forms of cold urticaria and emphasises the need for further studies to confirm its efficacy and identify patient profiles most likely to benefit.

Finally, for some individuals, a cold desensitisation may be considered. It involves gradual, controlled and localised exposure to cold, carried out exclusively in a specialised hospital setting. This approach requires close medical supervision.

• BIZJAK M. Cold urticaria: From wheals to anaphylaxis. The Journal of Allergy and Clinical Immunology (2006).

• BOYCE J. A. Successful treatment of cold-induced urticaria/anaphylaxis with anti-IgE. Food Allergy, Dermatologic Diseases, and Anaphylaxis (2006).

• MAURER M. & al. Cold urticaria – What we know and what we do not know. European Journal of Allergy and Clinical Immunology (2020).

• KRAUSE K. & al. Cold-induced urticarial autoinflammatory syndrome related to factor XII activation. Nature Communications (2020).

• MAURER M. & al. Risk factors for systemic reactions in typical cold urticaria: Results from the COLD-CE study. European Journal of Allergy and Clinical Immunology (2021).