15 Most Common Allergy Triggers and Reactions

Black Henna Tattoos You have probably seen the gorgeous designs that are drawn on the hands of Hindu brides, among others. Many people would love to… Simi - January 30, 2018

Black Henna Tattoos

You have probably seen the gorgeous designs that are drawn on the hands of Hindu brides, among others. Many people would love to take the opportunity to have their hands similarly decorated at fairs and festivals. To be clear, real henna is not black but burnt orange or brown in color. Henna temporarily stains the skin a dark red color. The paste is used by those offering black henna temporary tattoos.

The main culprit in the black “henna” is a chemical called para-phenylenediamine (PPD), which is usually an ingredient in hair dye. In commercial products like hair color, it is strictly controlled. Home dye kits carry explicit instructions and warnings about how the dye is managed, with plastic gloves to protect the hands and clear instructions and warnings about how long the dye should stay in the hair.

Some people can still react badly to hair dye even after following the instructions to the letter. Hobby henna artists, however, are not controlled. Some people react to the PDD with a burning sensation. Some people may feel a little discomfort, such as burning or tingling, while others experience real chemical burns, with severe pain, swelling, redness, and blisters. Some people now have the shape of the original pattern of the henna design etched into their skin by burned tissue!

Even in less severe cases, a bad reaction to a henna tattoo can leave you sensitized or oven allergic to PPD and you may experience an adverse reaction in the future when you use hair dye, even though you have used it before. So always carry out the allergy test prescribed in the instructions even though you have used the hair dye before.


While many people joke about being “allergic to exercise” it is a real, though rare, phenomenon. It is called Exercise-induced anaphylaxis (EIA). It is often triggered by vigorous exercise, but cases exist where merely walking or gardening was sufficient to induce an attack. Often, certain additional factors other than exercise contribute to the attack, such as certain foods, alcohol, temperature, drugs (e.g., aspirin and other nonsteroidal anti-inflammatory drugs), humidity, seasonal changes, and hormonal changes can all contribute to the attack.

Often different combinations of factors can precipitate an attack. While food is often a factor, the attacks only occur where both factors contribute. Foods that are often implicated in allergies are frequently implicated as co-factors here, although many other foods can help instigate an attack. In one case, a combination of two specific foods was required to instigate an attack. In other cases, any food at all would suffice.

Sometimes the co-factor has been an inhalant such as those related more to hay fever or other allergies. Just to add to the confusion, there is some evidence that genetics may also play a part and that susceptibility for EIA may be inherited. As yet, we do not fully understand the interplay of the many factors which can contribute to EIA. Attacks are often not caused by the same co-factors.

Treatment is limited to reducing and monitoring exercise levels and trying to tie down trigger factors in individuals. Scientists believe that the confusion of factors involved may mean that the prevalence of the disorder has been underreported in the past and that more people are affected by the condition. Indeed, they believe that the incidence of the ailment is increasing.

Cold Hives

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 inducements, 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 suffers 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 mild 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.

Hairy Caterpillars

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 injuring 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 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.