Cold urticaria or Cold Hives, is a condition where hives or weals are induced on the skin by cold or wet weather, after swimming in cold water or even with some ice cubes. Sweat cooling on the skin on a hot day may be enough to initiate an attack. In fact, any quick reduction in temperature may be enough to start an attack after only a few minutes of exposure.
These hives may remain for a minute or two or up to a few days. Other symptoms can include swollen or red hands. Although these are common reactions to cold, the hands will swell under minor inducement, such as holding a cold glass. Equally, red hands which stay red for longer are another diagnostic measure. Severe cases begin to show symptoms of dizziness or even anaphylactic shock, although rarely to a life-threatening degree.
It is estimated that only one person in a million suffer from this disorder to a degree where they are diagnosed with the disorder, but between 15 and 25% of people may experience the disorder during their lives, though usually so mildly that they may not even notice. The weals usually itch, as may the hands and feet, which may also swell. There seems to be a genetic factor to the condition, although other cases show no familial precedent.
As yet, there is no scientific explanation as to why people suffer from this disorder. Antihistamine treatments are effectively prescribed for this condition. Under medical supervision, patients should try and establish the conditions which will induce an attack by looking at factors like temperature thresholds and the length of exposure required to induce an attack in order to help people manage their condition adequately.
Some caterpillars, such as the gypsy moth, have hairs or fibers on their body which can break off, embed themselves in human skin, and irritate or transmit a toxin into the skin. Magnified, the barbed hairs resemble tiny versions of a porcupine’s quills, except that they contain a poison sac. Usually, it is necessary to touch the caterpillar to be stung, as the hairs are completely defensive and cannot be actively administered; but sometimes loose hairs can also cause irritation.
Most cases are caused by accidentally brushing against a caterpillar, although children may find these baroque caterpillars too fascinating to ignore. Sometimes loose hairs can be inhaled, causing breathing problems; or even injure an eye. Touching some species of these caterpillars may cause only a mild tingling sensation, while touching other species may cause instant pain, followed by irritation for a period after and a raised, red weal or rash.
The severity of the injury depends partly on the sensitivity of the patient, the severity of the contact and the species of caterpillar. In most cases, symptoms are a reddening and swelling of the skin and small bumps which are gone within the hour. More severe symptoms may include itchiness, blistering, or eczema-like symptoms which may last for weeks.
Antihistamine or hydro cortisol creams are usually effective. In their absence, an ice pack or a paste of baking soda will usually provide relief. Placing a piece of tape, preferably duct tape, on the affected skin and then pulling it off sharply is a good way of removing the hairs embedded in the skin. Wash the area well and wash all clothes thoroughly to remove any loose hairs which may remain.