93 Fun Facts About Allergies

Which common digestive problem, caused by lacking an enzyme, is often mistaken for a milk allergy?

Lactose intolerance is a shortage of the gut enzyme lactase, not an immune reaction, so undigested milk sugar causes bloating and cramps instead of an allergic response.

What is the most common immediate treatment for a severe allergic reaction?

Epinephrine is the first-line treatment for anaphylaxis, a severe and potentially life-threatening allergic reaction, and works quickly to reverse symptoms.

Which antibody is primarily responsible for mediating allergic reactions?

IgE is thought to have evolved to fight parasitic worms and venoms; in allergy the same antibody raises the alarm over harmless things such as pollen.

What common environmental allergen comes from trees, grasses, and weeds?

Pollen from trees, grasses, and weeds is a widespread outdoor allergen, causing seasonal allergic rhinitis, commonly known as hay fever.

Hay fever in Japan is caused primarily by pollen from which tree?

Sugi, the Japanese cedar, was planted en masse after World War II for timber, and its spring pollen now triggers hay fever in a large share of the country's population.

What type of cells release histamine during an allergic reaction?

Mast cells live in the skin and in the linings of the airways and gut, packed with granules of histamine, which is why a reaction shows first as hives, sneezing or cramps.

Which chronic skin condition, often linked with allergies, is marked by itchy, red, dry and inflamed patches?

Eczema, or atopic dermatitis, may begin because the skin lacks proteins that keep its barrier watertight; it usually starts in infancy and many people outgrow it.

Which common food allergen is a legume?

Despite their name, peanuts are botanically legumes, not tree nuts, and are one of the most common and potent food allergens.

Which food became the ninth mandatory allergen on US food labels in 2023?

Sesame joined the list under the FASTER Act of 2021, and labels had to name it from 1 January 2023, though food already on shelves did not have to be relabelled.

What is the medical name for hay fever, an allergic inflammation of the lining of the nose?

Allergic rhinitis has a misleading nickname: despite 'hay fever', it typically brings no fever, and the trigger is wind-borne pollen, not hay.

How do antihistamine medicines relieve allergy symptoms?

Block histamine receptors is all they do: the histamine is still released, but it can no longer deliver its message to cells, so itching, sneezing and a runny nose ease.

Which condition causes itching or swelling within minutes of eating certain raw fruits or vegetables?

Oral Allergy Syndrome strikes when proteins in raw produce resemble pollen proteins; heat breaks them down, so an apple that itches raw is usually harmless cooked.

How do allergies to indoor triggers typically differ from pollen allergies?

They occur year-round because the triggers live in the house all year, whereas pollen is in the air only while particular plants are in flower.

Which type of medication is the most effective routine treatment for persistent hay fever, calming inflammation inside the nose?

Corticosteroid sprays are the most effective treatment because they calm the inflamed lining itself, and they work best used every day, not only when symptoms flare.

Which metal, common in cheap jewellery, coins, zips and buttons, causes an itchy contact rash in many people?

Nickel causes so many contact rashes that Europe regulates it: what counts is not how much nickel an item contains but how much its surface releases onto the skin.

Which kind of pollen is the most common trigger of hay fever worldwide?

Grass pollen, above all from ryegrass and timothy, rides the wind into noses; bright garden flowers are rarely to blame, because insects carry their pollen.

What is the medical term for hives, an itchy rash characterized by raised, red welts on the skin?

Urticaria comes from the Latin for nettle, since the welts look like a nettle sting; each one usually fades within hours, even as new ones rise elsewhere.

What preservative compound in some foods and wines can trigger asthma-like symptoms in sensitive people?

Sulfites set off reactions in enough people with asthma that in 1986 the FDA banned their use on fruit and vegetables served or sold raw, such as salad-bar lettuce.

What type of immunotherapy involves placing drops or tablets under the tongue to treat certain allergies?

Sublingual immunotherapy (SLIT) trains the immune system with small doses of the very thing that sets it off, and many people prefer it because it replaces a course of injections.

Where should an epinephrine auto-injector such as an EpiPen be injected in an emergency, through clothing if necessary?

The middle of the outer thigh, over the vastus lateralis muscle, so the drug reaches muscle quickly; it can go straight through clothing.

Which microscopic creature, a major indoor allergy trigger, feeds on shed skin in warm, humid bedding and carpets?

Dust mites neither bite nor burrow; the trouble comes from their droppings, which build up in bedding and are breathed in.

Which chronic condition, in which inflamed and narrowed airways cause wheezing, is often allergic and managed with inhalers?

Asthma is often set off by breathing in an allergen, which makes the muscles around the airways tighten and their lining swell.

What is the term for swelling beneath the skin, often around the eyes or lips, that can accompany hives?

Angioedema is the deeper cousin of hives, swelling the tissue under the skin instead of its surface, and it becomes an emergency if the tongue or throat swells.

What nickname is given to oral anaphylaxis caused by eating flour infested with tiny arachnids?

Pancake syndrome got its name after people fell ill eating pancakes made from flour that had sat in humid storage and filled with mites.

What is the characteristic habitual upward nose-rub of chronic hay fever sufferers called?

The allergic salute, an upward swipe of the palm across an itchy nose, can leave a permanent line across the bridge if the habit goes on long enough.

What type of allergic reaction is triggered by consuming red meat, often linked to a tick bite?

Alpha-gal syndrome is unusual twice over: the trigger is a sugar, not a protein, and symptoms can start 3 to 8 hours after the meal, often in the middle of the night.

Montelukast treats allergic asthma and hay fever by blocking receptors for which inflammatory mediators?

Leukotrienes narrow the airways and inflame them; montelukast blocks their receptors, but mood and sleep side effects mean that for hay fever it is kept for people who cannot be treated with other medicines.

Which common allergy trigger grows both indoors and outdoors in damp environments?

Mold, a type of fungus, releases spores that can act as allergens and thrive in damp indoor and outdoor environments, triggering respiratory and skin allergy symptoms.

Which oily compound in poison ivy sap triggers its itchy, blistering rash?

Urushiol clings to clothing, tools and pet fur, sometimes for years, so people can get the rash without ever touching the plant.

Which common food allergen is often found in baked goods, pasta, and cereals?

Wheat allergy is an immune reaction to wheat proteins and is not the same thing as celiac disease, an autoimmune reaction to gluten that damages the gut lining.

Which allergy blood test, originally a radioimmunoassay, measures antibodies to specific allergens?

RAST, the radioallergosorbent test, was a 1974 brand name and its maker replaced the method in 1989, yet allergy blood tests are still often called by it.

Which common indoor allergen is made up of microscopic skin flakes and dried saliva?

Pet dander, not hair, is the problem: a cat's allergens come from its skin and saliva, so hair length makes no difference and no breed has been shown to be allergy-free.

After months of weekly build-up injections, allergy shots move into which phase, lasting three to five years?

Maintenance begins once the full dose is reached: the shots drop from weekly to once every few weeks, and the relief often lasts for years after the course ends.

Which chronic allergic condition causes swallowing difficulty and food getting stuck in the esophagus?

Eosinophilic esophagitis is named for the white blood cells that crowd the gullet's lining; because foods drive it, a strict six-food elimination diet is a standard treatment.

Loratadine and cetirizine, which cause less drowsiness than older antihistamines, belong to which generation?

Second-generation antihistamines, such as loratadine and cetirizine, are known for causing less drowsiness compared to older, first-generation antihistamines because they cross the blood-brain barrier less readily.

Which hypothesis links the rise in allergies to modern childhoods with too few infections and microbes?

The hygiene hypothesis dates from 1989, when David Strachan found hay fever was rarer in children from large families, who caught more infections from their siblings.

Tropomyosin, a protein also found in house dust mites, is the main allergen in which food?

Shellfish and mite allergy overlap because tropomyosin is so alike across invertebrates: people sensitised to mites can react to shrimp, crab and lobster too.

Which allergy, common among healthcare workers, is triggered by gloves, balloons and condoms?

Latex allergy builds with repeated exposure to natural rubber proteins, which is why children who have had many operations are at risk alongside glove-wearing health workers.

How does epinephrine counteract an anaphylactic reaction?

It works to constrict blood vessels and open airways: raising blood pressure through vasoconstriction, relaxing the airway muscles (bronchodilation) and increasing cardiac output.

Which diagnostic method is the 'gold standard' for confirming a food allergy?

An oral challenge settles the question because skin and blood tests show only that antibodies exist, not that the food actually makes the person ill.

Allergic contact dermatitis from poison ivy is which type of hypersensitivity reaction?

Delayed hypersensitivity is run by T cells, not antibodies, which is why a poison ivy rash takes a day or more to appear instead of the minutes an immediate allergy needs.

Which exercise-triggered condition can progress from hives to a dangerous drop in blood pressure?

Exercise-induced anaphylaxis often needs a second trigger: in many patients neither the exercise nor a particular food does harm alone, but the two together set off a reaction.

What term describes an immediate wheal-and-flare reaction where an allergen has touched the skin?

Contact urticaria appears within minutes where the skin was touched and fades within hours, whereas contact dermatitis takes days or weeks to heal.

Which symptom, despite the nickname of seasonal pollen allergy, points to a cold or flu instead?

A high temperature is not part of hay fever, which got its name because it peaks in haying season. Allergy symptoms also tend to outlast a cold, often dragging on for more than two weeks.

Which household pet secretes Fel d 1, an allergen made mainly in its saliva and skin glands?

Cats carry Fel d 1, the trigger for about 90% of people with a cat allergy, and unneutered males make more of it than females or neutered males.

Which antibiotic allergy is claimed by about one person in ten yet disproved in most who get tested?

Penicillin allergy labels are wrong about nine times in ten: of the roughly 10% of people who report one, some 90% turn out not to be allergic to the drug.

In which 1991 film does Macaulay Culkin's allergic character die after knocking down a beehive?

My Girl sends Thomas J back to the woods alone to find his friend Vada's lost mood ring, unaware that the hive the pair knocked down is still active.

What weather overwhelmed Melbourne's ambulance system with breathing emergencies in November 2016?

A thunderstorm is thought to make soaked pollen grains burst into fragments small enough to slip past the nose into the lungs. Emergency cases rose ten-fold and ten people died.

Which 1989 idea from David Strachan blames rising allergy rates on fewer early childhood infections?

Hygiene hypothesis thinking began with a family-size clue: seasonal allergies were less common in children from larger families, who presumably caught more infections from their siblings.

Which sweet folk remedy for seasonal pollen allergies has only inconclusive evidence behind it?

Local honey is often advocated for seasonal sneezing, yet the scientific evidence is inconclusive, and for allergic eye symptoms it is generally considered ineffective.

The antibody class behind most allergies is thought to have evolved mainly to fight which invaders?

Parasitic worms such as Schistosoma are the likely original target: the antibody co-evolved with the cells that release itch-and-swelling chemicals, a defence that misfires on harmless pollen.

Which insect pest leaves allergens in the dust of many homes with no visible sign of infestation?

Cockroaches turn up as allergens in the dust of roughly 20–48% of homes with no visible sign of the insects, so a clean-looking kitchen proves little.

Which red, itchy, watery eye condition is most often set off by pollen season in its allergic form?

Conjunctivitis inflames the thin membrane covering the white of the eye. The bacterial and viral kinds are contagious, spreading between people or on contaminated objects.

Which air filter standard, descended from paper in World War II gas masks, traps airborne pollen?

HEPA filters must remove at least 99.97% of particles 0.3 micrometres across, a bar that grew out of filter paper found inside a German gas mask.

Which stinging insects, accidental arrivals in the United States from South America, cause venom allergies?

Fire ants sting more than 14 million people in the United States each year, and between 0.6% and 6% of people may suffer a life-threatening whole-body reaction.

Which 2018 family film led Sony to apologise after an allergic man is pelted with blackberries?

Peter Rabbit has the rabbits pelt Thomas McGregor until a berry lands in his mouth and he needs his injector pen, a scene groups in several countries condemned as allergy bullying.

Which common painkiller triggers breathing attacks in people with Samter's triad?

Aspirin and related anti-inflammatory painkillers set off the attacks, yet avoiding the drugs does not stop the underlying disease, with its polyps in the nose, from developing or persisting.

Kounis syndrome is an allergic reaction that cuts blood flow through arteries feeding which organ?

Heart arteries can go into spasm, or a plaque can break free and block one, when an allergic reaction floods the body with inflammatory chemicals, bringing on chest pain.

Which allergy check puts drops of purified allergen on the forearm and nicks the surface under each?

Skin prick test sessions can give answers within minutes, and each one includes a drop most people react to and a glycerin drop that should do nothing, proving the skin is behaving.

Which 1923 term, from the Greek for being out of place, names a predisposition to allergies?

Atopy was coined by Arthur Coca and Robert Cooke, and the Greek word behind the name can also mean absurdity.

Which French physiologist won a 1913 Nobel Prize after toxin left dogs violently reactive instead of immune?

Charles Richet and Paul Portier began the work in 1901 aboard the Prince of Monaco's ship, extracting toxin from stinging sea creatures such as sea anemones.

Which Austrian paediatrician coined the word allergy in 1906 while studying reactions to horse serum?

Clemens von Pirquet noticed that patients given a second injection of horse serum or smallpox vaccine reacted more quickly and more severely than the first time.

The plants behind most seasonal allergies rely on what to carry their tiny, hardly visible pollen?

Wind-pollinated plants are the main culprits, and in northern latitudes the worst tree offender is birch, which affects an estimated 15–20% of hay fever sufferers.

In which 1993 comedy does Robin Williams's character lace an allergic rival's jambalaya with cayenne pepper?

Mrs. Doubtfire is Daniel in disguise, and when Stu starts choking the guilt-ridden nanny saves him with the Heimlich manoeuvre, which makes the prosthetic mask slip off.

Which tissue brand, sold in 1924 as a cold cream remover, was later pitched for colds and hay fever?

Kleenex's makers at first turned down their head researcher's idea, then gave it a little ad space, and by the 1930s the disposable handkerchief had become the main use.

Which dog breed did the Obamas pick for the White House partly because of daughter Malia's allergies?

Portuguese Water Dog coats are fleecy and shed little, the reason the breed is promoted to allergy sufferers; the Obamas' puppy Bo was a sibling of Senator Ted Kennedy's dog Cappy.

Which pairs of relatives turn out to share the same allergic disease about 70% of the time?

Identical twins match about 70% of the time against roughly 40% for non-identical pairs, strong evidence that allergic diseases run in families.

What colour of pumpkin on a Halloween doorstep signals non-food treats for children with food allergies?

Teal pumpkins began with a food allergy support group in East Tennessee, and since 2014 a national charity has promoted the idea so that every child can go trick-or-treating.

A flight surgeon who entered returned space capsules developed apparent allergic reactions to what?

Lunar dust clung to the capsule interiors, and his reactions worsened after each exposure; the sharp, sticky particles reportedly smell and taste of spent gunpowder.

Which antihistamine brand contains diphenhydramine, a 1946 drug also taken for insomnia and motion sickness?

Benadryl's active drug was developed by George Rieveschl, and the same compound is sold as a sedative as well as for allergic symptoms and itching.

Laboratory workers who become allergic to mice and rats react mainly to proteins in the animals' what?

Urine carries the culprits, known as major urinary proteins, and an estimated 11–30% of at-risk workers worldwide are affected.

Which complaint, common in hay fever, do doctors also call upper airway cough syndrome?

Post-nasal drip may be less abnormal than it feels: some researchers argue that mucus flowing down from the nose is a normal process in every healthy person.

Which crossbreed did Australian Wally Conron introduce as a low-shedding guide dog for people with allergies?

Labradoodle inventor Wally Conron hoped the catchy name and the allergy claims would offset the stigma attached to mixed breeds and help him sell the puppies.

What have allergen researchers concluded about the dog breeds marketed as hypoallergenic?

Breed is not a significant factor, researchers say: allergen levels vary from one individual dog to the next, and studies have found no significant differences between breeds.

Auto-injector pens carried by allergy patients were first developed to deliver antidotes to what?

Nerve gas antidote kits for soldiers came first; Sheldon Kaplan then adapted the idea in the mid-1970s into the pen that won US approval in 1987.

In which Oscar-winning 2019 film do schemers exploit a housekeeper's peach allergy to get her dismissed?

Parasite's Kim family use the allergy to convince her employer that she has tuberculosis; director Bong Joon-ho borrowed the detail from a university friend with the same allergy.

Bill Frankland, the allergist who popularised pollen counts, flew out in 1979 to treat which president?

Saddam Hussein was told that his breathing trouble was no allergy and that he should give up his habit of 40 cigarettes a day.

Which backfiring effect can set in after five to seven days of using decongestant nose sprays?

Rebound congestion, a blocked nose without sneezing, is suspected to follow overuse of sprays such as oxymetazoline that tighten blood vessels in the lining of the nose.

Which decongestant has been restricted since 2005 because it can be used to make methamphetamine?

Pseudoephedrine can be chemically converted into the illegal stimulant, though the decongestant itself is substantially less potent than that drug or cocaine.

Why did city planners historically favour male street trees, a habit critics call botanical sexism?

Less seed and fruit litter was the aim, but the horticulturist Tom Ogren argues that the surplus of male trees drives up pollen counts, a trade-off he gave its pointed name.

Which shade tree have some North American cities banned from planting because of its abundant pollen?

Mulberry pollen comes only from male trees and is light enough to be inhaled deep into the lungs, where it can set off asthma.

Which element in seafood is wrongly blamed for reactions to X-ray contrast dye?

Iodine allergy does not exist: seafood reactions target a muscle protein, and a seafood allergy raises the risk from contrast dye no more than a fruit allergy does.

Bird fancier's lung, also called pigeon lung, is an allergic reaction to dust from feathers and what else?

Droppings dry into a fine dust that carries bird proteins into the lungs, where the immune system's overreaction inflames the tissue.

Which unproven technique, also called muscle testing, is sold as a way to diagnose allergies?

Applied kinesiology has no evidence of diagnostic validity, American allergy specialists have ruled, and one study rated it no more useful than random guessing.

Histamine-releasing neurons in the brain's hypothalamus normally help to promote which state?

Wakefulness depends partly on histamine neurons in the hypothalamus, which is why older antihistamines that reach the brain cause drowsiness.

Why does a person's first-ever bee sting almost never set off an allergic reaction to the venom?

The body is not yet primed on a first encounter: allergic reactions are provoked by re-exposure, after the immune system has made antibodies against the venom.

Carl Prausnitz had serum from allergic colleague Heinz Küstner injected into his own skin, then ate which food?

Fish made the injection site turn hot, red and swollen, showing that something in Küstner's blood carried the allergy; physicians once used the transfer test that bears both names.

In the Gell and Coombs classification, the immediate reactions behind most allergies carry which label?

Type I sits apart from types II, III and IV, though the relevance of the whole scheme is now questioned and it has limited use in clinical practice.

Which white blood cells, only about 0.5% to 1% of those in circulation, store histamine and heparin?

Basophils are the least common type of granulocyte, and like their tissue-dwelling counterparts they secrete their histamine when stimulated.

Which process, shared with natural killer cells, has allergy cells release chemicals stored in tiny sacs?

Degranulation empties the cell's granules, and in an allergy it is set off when antibodies already sitting on the cell surface meet their trigger.

Which molecules, named from the Greek for fasten, provoke immunity only when bound to a carrier protein?

Haptens emerged from the work of the Austrian immunologist Karl Landsteiner, who built synthetic versions to probe how the immune system recognises chemicals.

Histamine, the chemical behind allergy symptoms, also signals cells in the gut lining to release what?

Stomach acid is switched on when cells in the stomach wall release histamine, which spurs the neighbouring acid-making parietal cells into action.

Which drug company raised the wholesale price of an EpiPen two-pack about 500% between 2009 and 2016?

Mylan lifted the wholesale price from about $100 to around $609 while holding roughly 90% of the market.