15 Most Common Allergy Triggers and Reactions

Food Food allergies are an abnormal immune response to specific foods. Food intolerance differs from allergic reactions, where people either struggle to easily digest certain foods… Simi - January 30, 2018


Food allergies are an abnormal immune response to specific foods. Food intolerance differs from allergic reactions, where people either struggle to easily digest certain foods – milk and wheat are common causes of intolerance, or show skin problems such as eczema. The symptoms of an allergy are quickly apparent while those of intolerance take time to manifest. Although the symptoms may not be as severe as allergies can be, intolerances can be as disruptive as any allergy.

Milk, shellfish, nuts, and wheat are among the most common foods that cause allergies. Symptoms, which can include asthma, hives or rashes, vomiting, diarrhea and swelling round the mouth, can be severe and may include difficulty breathing or collapse. It is believed that around 4 to 8% of people have at least one food allergy, varying across a wide spectrum of severity.

They are more common in children (especially boys) than adults, with the prevalence increasing in developing countries. There is a genetic aspect to food allergies, and children of parents with food allergies have a much higher chance of having one. Try your child on small amounts of foods that are well-known allergens, then wait and see how they respond. Be particularly careful with foods known to cause severe reactions in some people, like nuts and shellfish.

Educate your child as much as possible if they have a food allergy. Allergenics appear as ingredients in some surprising foods!  Always keep the appropriate treatments to hand, including an EpiPen. Children may outgrow minor food intolerances or allergies, such as milk or wheat, so re-test these foods carefully as they grow. Children with severe reactions to things like nuts or shellfish will always have that allergy.


While perfume comes to mind under this rubric, many ordinary household items that contain fragrances of one kind or another. Think of soaps and shampoos; cleaning products and air fresheners; as well as laundry detergents, cosmetics, and scented candles. Allergic reactions to these products vary across the people who encounter them, and the variety of chemicals involved, which makes it hard to offer a standardized description of this allergy.

There are about 100 chemicals in common use as fragrances, but 5,000 chemicals that fall under this banner. Symptoms vary from mild to severe, but usually ease immediately away from the scent. For some, symptoms get worse the more often the fragrance is encountered. Many scientists argue that fragrances are an irritant rather than an allergen. Irritants do not impact the immune system but irritate sensitive membranes such as the skin or the sinus system.

The most common symptom is sneezing, but symptoms such as contact dermatitis, asthma, and headaches, among the many others, often require medical help or advice. Around 2-4% of people react badly to require medical attention, but up to 30% of the population declare themselves sensitive to some fragrance or other, with 20% of people reacting to air fresheners, and 10% to laundry detergents.

Products marked “fragrance-free” may still contain some fragrance chemical or another, although they don’t usually cause the same problems. People who suffer from asthma or whose sinuses are inflamed through illness are often more sensitive to fragrances.  The best way to deal with this problem is simply to try and stay away from these chemicals. This means identifying and eschewing products which produce symptoms for you, buying fragrance-free products over others where possible.

Cell Phones

Cell phone use causes a number of medical problems, from car crashes to bumps and bruises from not paying attention to where you walk. Here we are only interested in the allergic reaction some people experience from talking too much on the phone. Nickel, cobalt, and chromium in the phone case can all cause contact dermatitis if the phone is held to your ear for extended periods, with nickel identified as the most common villain.

Nickel-related Allergic Contact Dermatitis (ACD) usually affects wearers of jewelry. A lot of gold-plated jewelry, such as pierced earrings has nickel content and up to 17% of American women and 3% of men have suffered symptoms. Certain phones with a metal casing are the main cause of ACD, with around 10% of people showing a sensitivity to nickel. Extended talking or typing can cause, red, itchy ears, cheekbones or hands.

Other symptoms of prolonged use include dry, itchy skin like eczema, redness, blistering, lesions, and even oozing on the face or ears, but most of these are rare. Carrying the phone close to your skin can also cause ACD, such as girls tucking their phone into their bras, or thighs when they are kept in pockets. It will surprise nobody to know that more than half those diagnosed were teenagers.

The first case of ACD was diagnosed in 2000, with a 40% increase in cases in the short period from 2010 to 2012. Preventative measures are obvious: Consider purchasing a phone with a non-metallic frame, use a headset for phone calls or buy a protective plastic cover that covers the face of the phone as well as the back. Many phone manufacturers have stopped using metal casings.

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 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 instruction and warning 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 burn 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 which 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 a 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 involve 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 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.

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 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.