Anaphylaxis: Recognizing and Responding to a Severe Allergic Reaction

Severe allergic reactions do not always look dramatic at first — a few hives, a tickle in the throat, mild nausea. But within minutes, the same reaction can turn into anaphylaxis, a life-threatening emergency that can close the airway or crash blood pressure. A 2020 study of 699 people in Tangail district found that brinjal (eggplant) was the single most common food-allergy trigger in Bangladesh, responsible for 28.3% of cases — and worryingly, just over half of allergic patients treated themselves at home without ever consulting a doctor. That gap between how common allergic reactions are and how rarely people seek proper care is exactly why anaphylaxis is widely under-recognized and under-treated in Bangladesh.

What Is Anaphylaxis?

Anaphylaxis is a sudden, severe, whole-body allergic reaction. It happens when the immune system — primed by a previous exposure to a substance — overreacts on a later exposure, releasing a flood of chemicals (including histamine) that affect the skin, airway, gut, and circulatory system all at once. Unlike a mild, localized allergy (say, itchy skin after touching a plant), anaphylaxis involves two or more body systems or causes breathing difficulty or a drop in blood pressure on its own.

Reactions can begin within seconds of exposure, though they can also take up to about an hour to appear. The speed and severity depend on the trigger, the amount of exposure, and the individual's sensitivity — the same person can react differently to the same allergen on different occasions.

Common Triggers

According to Bangladesh-focused and international allergy references, the most frequent causes of allergic reactions — including the most dangerous ones — fall into three groups:

• Food: milk, egg, prawn and shrimp, wheat, certain fish, beef, and — notably in Bangladesh — brinjal (eggplant), which was linked to itching in about 28.5% and skin rash in about 22.7% of reported cases in the Tangail study.
• Drugs: antibiotics, especially the penicillin family, and non-steroidal anti-inflammatory drugs (NSAIDs) are the most frequently implicated medicines. Sulfa drugs, anticonvulsants, and insulin are also recognized triggers. Drug-related reactions are less common than food reactions but tend to appear more in adults.
• Insect stings: bees, wasps, hornets, and ants (hymenoptera) are among the most dangerous triggers and can cause anaphylaxis within minutes of a sting.

Other recognized triggers include latex, certain cosmetics and dyes, industrial chemicals, and — for airborne allergies rather than anaphylaxis — pollen, house dust, and animal dander. Family history matters: a person with an allergic relative has a higher chance of developing allergies themselves.

Recognizing the Symptoms

Anaphylaxis can affect several systems simultaneously. Knowing the pattern — not just a single symptom — helps you recognize an emergency quickly.

• Skin/mucosal: widespread hives, intense itching or flushing, swelling of the lips, tongue, uvula, or face.
• Respiratory: a feeling of throat closing, hoarseness, stridor (a harsh breathing sound), wheezing, coughing, or shortness of breath.
• Cardiovascular: dizziness, fainting, a weak or rapid pulse, or a sudden drop in blood pressure.
• Gastrointestinal: nausea, vomiting, diarrhea, and abdominal pain.
• General: a sense of impending doom is a commonly reported — and clinically significant — warning sign.

In infants, the signs can be subtler: sudden drooling, unusual sleepiness, or inconsolable fussiness and crying can be the only clues, since babies cannot describe throat tightness or dizziness.

How Doctors Confirm Anaphylaxis

A clinician can usually diagnose anaphylaxis from the history and physical exam alone — blood tests are used only in select cases. The widely used World Allergy Organization criteria consider anaphylaxis highly likely when either of these patterns is present:

• Acute skin or mucosal symptoms (hives, itching, swollen lips/tongue) together with breathing difficulty, low blood pressure, or other organ involvement — gastrointestinal symptoms support but do not confirm the diagnosis on their own.
• Acute hypotension, bronchospasm, or laryngeal symptoms after exposure to a known or probable allergen, even with no skin symptoms at all. For adults, hypotension means a systolic blood pressure under 90 mmHg or a drop of more than 30% from the person's baseline; for children under 10, it means a systolic pressure under roughly 70 + (2 × age in years).

This second pattern is important to know: a severe reaction without any visible rash is still anaphylaxis and still needs emergency treatment.

First Aid: What to Do in the First Minutes

Anaphylaxis is a medical emergency. Acting in the first few minutes genuinely changes outcomes.

• Call for emergency medical help immediately — do not wait to see if symptoms worsen. Go to the nearest hospital emergency department or call for an ambulance without delay.
• Use epinephrine (adrenaline) right away if it has been prescribed and is available. Epinephrine is the first-line treatment for anaphylaxis, and delaying it is linked to worse outcomes, including a higher chance of the reaction returning later (see "biphasic reactions" below).
• Keep the person lying down with legs raised if they can tolerate it, and do not let them stand or walk — sudden standing can cause a dangerous drop in blood pressure. If they are struggling to breathe, allow them to sit in whatever position helps them breathe most easily.
• Do not let the person shower or bathe during a reaction, as this can worsen a drop in blood pressure.
• Stay with them and monitor breathing and responsiveness. If they stop breathing normally or become unresponsive, begin CPR.
• A second dose of epinephrine can be given around 5 minutes after the first if there is no improvement, if a second dose is available.
• Go to the hospital even if symptoms seem to improve on their own or after epinephrine — observation is still necessary.

It is a common and dangerous misconception that an antihistamine tablet is enough to stop anaphylaxis. Antihistamines (such as cetirizine, loratadine, or fexofenadine) and steroids (such as prednisolone or hydrocortisone) can help with itching, hives, and inflammation afterward, but they act too slowly and do not reverse airway swelling or a blood pressure crash — they are not a substitute for emergency treatment and epinephrine.

Biphasic Reactions: Why Observation Matters

A biphasic reaction is a return of anaphylaxis symptoms after they have already settled — usually within about 4 hours, though it can occur later. Estimates of how often this happens vary widely: some reviews cite up to 20% of cases, while a prospective study of 430 emergency-department anaphylaxis visits recorded biphasic reactions in 7.2% of patients. The same study linked delayed epinephrine administration to a higher risk of a biphasic reaction — another reason not to delay treatment or leave the hospital early. Risk factors for a second wave of symptoms include a severe initial reaction, needing more than one dose of epinephrine, an unidentified trigger, and reactions triggered by drugs, particularly in children. Anyone who has had a significant reaction should be observed at a medical facility for several hours, not sent home right after symptoms ease.

Anaphylaxis in Bangladesh: Access and Practical Realities

Epinephrine auto-injectors — the pre-filled pens widely used in high-income countries for emergency self-treatment — are not reliably available in much of South Asia, and regional reporting from a tertiary-care hospital in a neighboring country found adrenaline was not stocked even there, citing supply-chain and cost barriers. Standard injectable adrenaline ampoules are present in the Bangladeshi market (sold under brand names including Adrenaline, Adrin, Hyponor, and Levofed), but these are intended to be administered by a trained healthcare professional, not self-injected at home. In practice, this means the single most reliable action for anyone in Bangladesh facing a suspected severe allergic reaction is getting to a hospital or clinic with emergency facilities as fast as possible, rather than assuming home treatment will be sufficient. If you or a family member has had a severe reaction before, discuss with your doctor whether an emergency action plan and prescription epinephrine (where obtainable) make sense for your situation.

Who Is at Higher Risk

• People with asthma are at greater risk of a severe or fatal reaction, because their airways are already more reactive.
• Children may show subtler signs (drooling, sleepiness, fussiness) and can deteriorate quickly; a past reaction, known allergies, or family history raises risk.
• People who have had anaphylaxis before are at risk of a repeat reaction on future exposure — avoidance and a clear plan are essential.
• Elderly patients and those with underlying heart disease may have reactions complicated by their existing cardiovascular condition, and need careful medical assessment.

Mild Allergy or Anaphylaxis? Knowing the Difference

Not every allergic reaction is an emergency. A mild reaction usually stays localized — a patch of hives, itching at the site of contact, mild sneezing or watery eyes — without affecting breathing or circulation. Anaphylaxis, by contrast, involves multiple body systems, or breathing/circulation symptoms on their own, and can worsen within minutes. When in doubt — especially if there is any throat tightness, swelling of the face or tongue, breathing difficulty, dizziness, or widespread symptoms after a known trigger — treat it as an emergency rather than waiting to see if it passes.

Prevention and Long-Term Management

• Identify and strictly avoid known triggers — if a specific food, medicine, or insect has caused a reaction before, note it clearly and share it with family members and caregivers.
• Always tell every doctor, dentist, and pharmacist about any past drug reaction — even a mild one — before taking a new antibiotic or medicine, especially penicillin-based antibiotics.
• If you have had a serious reaction, ask your doctor about allergy testing, a referral to an allergist/immunologist, and whether carrying prescription epinephrine is appropriate for you.
• Read food labels carefully and ask about ingredients when eating out, particularly with shellfish, egg, milk, and — in the Bangladeshi context — brinjal/eggplant.
• Consider a medical alert bracelet or card noting your specific allergies, especially for children and for people with a history of severe reactions.

When to See a Doctor

See a doctor after any significant allergic reaction, even if it resolved on its own, to identify the trigger and discuss prevention. Seek emergency care immediately — do not wait for an appointment — for any reaction involving breathing difficulty, throat or facial swelling, fainting or severe dizziness, a rapid or weak pulse, or symptoms spreading across multiple parts of the body. General information here cannot replace an individual assessment; always consult a qualified doctor or pharmacist for diagnosis and treatment decisions specific to you or your child.

Sources: World Allergy Organization (WAO) anaphylaxis diagnostic guidelines, a 2020 cross-sectional food allergy study from Tangail district, Bangladesh, and general clinical references on anaphylaxis management and biphasic reactions.