Skin allergies range from a mild nuisance to a reaction that turns dangerous. The hard part is that the rash alone will not tell you which. You can keep even a sudden flare from turning serious.
What Are Skin Allergies?
Skin allergies happen when your immune system responds to an irritant, a harmless substance, as though it were a threat. On contact, your immune system makes antibodies and other defences against it, and your skin becomes red, itchy, and swollen.
Signs and Symptoms of Skin Allergies
Itchy skin is the most common sign of skin allergies, often with redness, irritation, and a warm, inflamed feeling. The rash itself can be flat or bumpy, and longer reactions can leave the skin dry and scaly. Hives appear within an hour or two of exposure to an allergen and fade within hours, while a contact rash develops over a day or two and can last one to two weeks.
Swelling of the lips, tongue, or throat, trouble breathing, or feeling faint mark a severe allergic reaction that needs emergency care rather than home treatment.
Plant Triggers
Plants are among the common triggers behind skin allergies. The most famous is poison ivy, but in Australia Grevillea is the standout, especially the Robyn Gordon hybrid, a widely planted shrub whose flowers and leaves cause an itchy, blistering rash. Chrysanthemums, primula, English ivy, and Rhus trees can all trigger allergic contact dermatitis as well.
A second group reacts only with sunlight. Lantana, parsnip, and celery can cause a rash on skin that is exposed to the sun after contact, a reaction known as photo-contact dermatitis.
Insect Bites and Stings
Insect stings are the trigger most likely to cause a severe reaction. Honeybees are the most common cause of insect allergies, followed by wasps, the Jack Jumper ant, and the imported fire ant. Wasps such as the European and paper wasp can sting more than once.
Most stings cause only a local reaction: an itchy welt and swelling that settles within a few days. A large local reaction, with swelling wider than 10 cm, lasts longer but is still not dangerous on its own. A sting that brings on trouble breathing or widespread swelling is a severe allergic reaction and an emergency.
Ticks call for extra care. Found mainly along the eastern coast, a tick bite can also cause a severe reaction, and the tick should be frozen with a spray and left to drop off rather than scratched or pulled, which can release more allergen.
Foods and Medications
Foods and medications trigger skin allergies from the inside, and the reaction usually appears as hives within an hour or two of eating the food or taking the drug. The foods behind most reactions are milk, eggs, peanuts, tree nuts, fish, and shellfish.
Several medications cause skin reactions too. Antibiotics such as penicillin, along with aspirin and other anti-inflammatory painkillers, can bring on hives. ACE inhibitors, taken for blood pressure, can cause angioedema without hives, sometimes months or years after the first dose.
Soaps, creams, and ointments can also cause an allergic rash, as can latex gloves. The cause may be a topical antibiotic such as neomycin, or a base ingredient such as lanolin, with the rash appearing where the product was used.
First Aid for a Skin Rash
First aid for a skin rash depends first on how serious the reaction is, since skin allergies range from a mild itch to a life-threatening emergency. A reaction that affects breathing, or that swells the lips, tongue, or throat, is a medical emergency: call 000, use an adrenaline injector such as an EpiPen or Anapen if one is available, and follow the person’s ASCIA action plan.
For a mild reaction, the first step is removing the trigger substance from the skin. Wash the skin with cool water and a mild soap to clear away any allergen, and take off jewellery or clothing holding the substance against your skin.
Cool water on a clean cloth, held against the skin for 10 to 15 minutes, eases the itching and brings down redness. Keep your nails short and avoid scratching, which can break the skin and let in infection. Calamine lotion or an oatmeal bath soothes a weeping rash. A non-drowsy antihistamine reduces itching and helps with hives, while a topical steroid such as 1% hydrocortisone calms a contact rash.
Enrol in First Aid Training
The many triggers behind skin allergies lead to a short list of reactions. Your judgement is what separates a few days of itching from a genuine emergency. First aid training gives you the response to spot a severe reaction, use an adrenaline injector, and get emergency help before things worsen.
FAQs
What's The Difference Between Eczema and an Allergic Reaction?
Eczema is a long-term condition where a weak type of skin leaves it dry, itchy, and prone to flares. These flares can happen with no single identifiable trigger.
What Is Contact Dermatitis?
Contact dermatitis is an itchy, inflamed rash where a substance has touched the skin. The rash can take the shape of what caused it, such as a band under a watch strap or a patch where a cream was applied.
What Is Atopic Dermatitis?
Atopic dermatitis is the medical name for eczema. The word atopic describes a tendency to react to allergens.
