Severe Allergy Reactions
Allergies are among the most common chronic health conditions worldwide and the symptoms range from mild to life-threatening. Discover types, causes, and effective treatment options for severe allergy reactions.
Written by Dr Shreya Sarkar
Last updated on 3rd Jul, 2025
Allergic reactions occur when the immune system reacts and attacks a foreign and typically harmless substance. They can range from mild to life-threatening. Severe allergic reactions can prove fatal and require immediate medical attention. Continue reading to explore the symptoms, causes, and available treatments for severe allergic reactions.
Understanding Severe Allergies
Allergies can affect people differently. Mild allergies are an inconvenience, but a severe allergic reaction can be life-threatening. A severe case of allergic response leads the immune system to release a flood of chemicals that can cause the body to go into shock- blood pressure drops suddenly, and the airways narrow, making breathing difficult. Severe allergy reactions need to be treated right away otherwise they can prove to be deadly.
Causes of Severe Allergic Reactions
Severe allergic reactions can be caused by several substances. These can include:
Foods: Peanuts, tree nuts, shellfish, milk, eggs, soy, and wheat are some of the most common triggers of acute allergic reactions.
Medications: Aspirin, antibiotics, and pain relievers that are available without prescription, as well as the intravenous (IV) contrast used in some imaging tests, can also cause severe allergic reactions.
Insect Stings: Stings from bees, wasps, yellow jackets, hornets, and fire ants can lead to a serious allergic reaction.
Latex: Natural rubber latex may cause a mild skin irritation or it can trigger a severe allergic reaction.
Physical Activity or Exercise: Although rare, severe allergic reactions can also occur after vigorous physical activity. Temperature, seasonal changes, drugs, alcohol, or eating certainfoods before exercise may be co-factors.
Types of Severe Allergic Reactions
Severe allergic reactions can happen in different forms. Learn about the most acute types of allergic reactions and how they can affect you.
Anaphylaxis: Also known as anaphylactic shock is a life-threatening allergic reaction involving the whole body and can occur within minutes of exposure to an allergen. Anaphylaxis can lead to hives and itchy, pale, or flushed skin.
Allergic Asthma: Allergic or allergy-induced asthma occurs when the body's immune system reacts to inhaled allergens like dust mites, pollen, animal dander, or mold spores, causing the airways to become inflamed and narrow, making it difficult to breathe. You may also experience chest pressure, wheezing, and cough.
Angioedema: Angioedema is the rapid edema, or swelling, of the area beneath the skin or mucosa. Although the condition is normally mild, it can be dangerous if it occurs in the throat or tongue, as it can make it difficult to breathe. If this happens, you should seek immediate medical help.
Symptoms of Severe Allergy Reactions
In most cases, severe allergy reactions occur within minutes, however, in certain cases, symptoms can occur a half-hour later after exposure. Symptoms include:
Low blood pressure (hypotension)
Reactions on skin including hives, itching, and flushed or pale skin
Swollen tongue or throat
Constriction of the airways, which can cause wheezing, coughing, and breathing difficulties
Nausea and vomiting
Stomach cramps and diarrhea
Weak and rapid pulse
Dizziness or fainting
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When to Seek Immediate Help
Seek emergency medical help if you or someone else you know is suffering from symptoms of a severe allergic reaction. Waiting for the symptoms to go away can be dangerous. If the person is carrying an epinephrine autoinjector, administer it right away. Watch the person for signs of increasing distress. Do not wait to see if the reaction gets worse. Avoid oral medicine if the person is having difficulty breathing.
Even if symptoms improve after the injection, you still need to go to an emergency room to make sure symptoms don't recur, even without more exposure to the allergen. This second reaction is called biphasic anaphylaxis.
Risk Factors and Triggers
There aren't many known risk factors for severe allergic reactions, but some things that might increase the risk include:
Exposure to Common Allergens: Exposure to allergens like food items, medications, insect bites, or stings can trigger a severe reaction.
Genetic Predispositions: Children born into families with a history of allergies are more likely to develop an allergic condition.
Environmental Influences: Factors like air pollution, chemical exposure, pets, infections, and feelings of stress and anxiety can contribute to the exacerbation of allergic reactions.
Diagnosis of Severe Allergy Reactions
If you suffer from severe allergy reactions, an allergist can evaluate your condition and help you manage your symptoms. Allergists are healthcare providers who specialise in allergies. They can help diagnose your allergies by performing physical exams and asking questions about previous allergic reactions.
Skin and Blood Tests
In case of severe allergy reactions, your allergist can run a series of tests. The most common allergy tests are skin prick tests and blood tests.
Skin-prick Test: An allergist will use a thin needle to prick your skin with a tiny amount of different possible allergens. They then check to see if your skin reacts to the allergen.
Blood Test: A healthcare provider draws a blood sample and sends it to a lab. Allergens are added to the sample and then it is tested for levels of IgE antibodies. This test has a higher rate of false positives, indicating you have an allergy when you really don't.
Challenge Test: You swallow a small amount of a suspected allergen, while an allergist and doctor closely monitor you in case you get anaphylaxis. If you do, you'll get an epinephrine shot right away to stop the reaction.
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Emergency Treatment Protocols
During a severe allergic reaction, you might receive cardiopulmonary resuscitation (CPR) if you stop breathing or your heart stops beating. You might also be given medications, including:
Epinephrine: To reduce the body’s allergic response
Oxygen: To help you breathe
Beta-agonist (such as albuterol): To relieve allergy-induced asthma symptoms
Intravenous (IV) Antihistamines and Cortisone: To reduce inflammation of the air passages
Emergency treatment is recommended even if symptoms start to improve. After a severe allergic reaction like anaphylaxis, it is possible for symptoms to start again. Being watched in a hospital for several hours most often is needed.
Long-term Management Strategies
Long-term management strategies for allergic reactions that are severe include:
Allergen Avoidance: This includes identifying and avoiding the allergens that are responsible for triggering severe allergic reactions. For example, if you know you are allergic to peanuts, you can check the labels before buying any food item and also inform your servers about your allergy when you are dining in a restaurant.
Epinephrine Autoinjector: Always carry a self-administered epinephrine autoinjector with you wherever you go.
Allergen Immunotherapy: Also known as allergy shots or desensitisation, allergen immunotherapy is a treatment that involves injecting small amounts of allergens to reduce the immune system’s reaction. This is an option that is often used for severe cases of allergies that do not respond to other treatments.
Lifestyle Changes and Precautions
The below given precautionary measures and lifestyle changes can help you manage your condition in a better manner:
Adapting Home and Work Environments: You can reduce your exposure to allergens like pollen, pet dander, and compounds in food, drinks, and personal hygiene products. For example, use fresh bedding and clothes every day and wear a face mask when you are at work. You should also take your medications as prescribed.
Allergy Action Plan: Wear a medical ID tag or alert bracelet and keep your epinephrine auto-injectors and other allergy medications with you at all times.
Educating Family and Friends: It is important to describe your allergy triggers to friends and family members. Also, educate them about your medications and the use of epinephrine in case of an emergency.
Prognosis and Complications
While allergies may seem benign, they can still significantly impact quality of life,
mental as well as overall physical health.
Chronic Conditions Related to Allergies: Untreated or under-treated allergies can increase the risk for more serious diseases, such as asthma, sinusitis, eczema, altered mood, and cognitive impairment.
Reduced Quality of Life: Whether you suffer from seasonal or year-round allergies, the impact on your day-to-day life can be significant. Your symptoms can limit your outdoor activities, and food choices and also impact your work or school performance.
Impact on Mental Health: Dealing with constant allergy symptoms, especially when they are severe, can cause stress, anxiety, and depression.
Conclusion
Severe allergy reactions like anaphylaxis require immediate medical treatment. It is crucial to be aware of the symptoms and how to respond. With the help of an accurate diagnosis and a successful management plan from a board-certified allergist, you can find comfort and live a healthy life.
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Consult Top Dermatologists
Dr. Hemalatha Naidu M
Dermatologist
5 Years • MBBS, MD (Dermatology)
Bangalore
Apollo 24|7 Clinic - Karnataka, Bangalore
(275+ Patients)
Dr Ritika Shanmugam
Dermatologist
9 Years • MBBS, MD (Dermatology, venereology, Leprosy)
Bangalore
Apollo 24|7 Clinic - Karnataka, Bangalore
Dr. K Chetana
Dermatologist
10 Years • MBBS, MD ( Dermatology)
Hyderabad
Apollo 24|7 Clinic, Hyderabad
Dr. Kavitha Killaparthy
Dermatologist
23 Years • MBBS,DIPLOMA(DERMATOLOGY,VENEREOLOGY,LEPROSY)
Hyderabad
JDS Skin & Hair Clinic, Hyderabad
Dr. Mayuri Jain
Dermatologist
11 Years • MBBS, MD Dermatology , Venereology & Leprosy
Delhi
Dr Mayuri Jain Clinic, Delhi
