Hypersensitivity Reaction Symptoms: When to Seek Help

What are the Types of Hypersensitivity Reactions?

There are four types of Hypersensitivity Reactions such as:

Type I: Immediate Hypersensitivity

Triggered by allergens such as pollen, pet dander, insect stings, or certain foods. These are common in conditions such as asthma,hay fever, and anaphylaxis.

Type II: Cytotoxic Hypersensitivity

Involves IgG or IgM antibodies directed against cell surface or extracellular matrix antigens, which leads to cell destruction. This is seen in conditions like hemolytic anemia and blood transfusion reactions.

Type III: Immune Complex-Mediated Hypersensitivity

Involves immune complexes (antigen-antibody complexes) that deposit in tissues and cause inflammation. Some examples are systemic lupus erythematosus (SLE) and rheumatoid arthritis.

Type IV: Delayed-Type Hypersensitivity

Mediated by T cells rather than antibodies. This reaction occurs hours to days after exposure to the antigen. Some examples are contact dermatitis and tuberculin skin test reactions.

What are the Causes of Hypersensitivity Reactions?

Hypersensitivity reactions occur when the immune system overreacts to a typically harmless substance such as pollen, food, or medication.

These exaggerated immune responses can range from mild discomfort to severe and life-threatening conditions.

The causes vary based on severity, duration, and environmental exposure.

Common Causes of Hypersensitivity Reactions include:

• Mild: Dust exposure, mild food allergens, insect bites.
• Moderate: Medication side effects, contact dermatitis (e.g., nickel or latex), seasonal allergies.
• Serious: Anaphylaxis due to peanuts or shellfish, autoimmune disorders, drug-induced hypersensitivity syndrome (DIHS).
• Acute: Sudden exposure to allergens like bee stings or IV drugs.
• Chronic: Ongoing exposure to environmental allergens or autoimmune triggers.
• Lifestyle and Environmental Triggers: polluted air, mold, certain foods, the use of cosmetics or perfumes, and extreme temperatures.

Conditions that Cause Hypersensitivity Reactions

Hypersensitivity reactions can be triggered by several underlying medical conditions that affect the immune system. These conditions may cause the body to respond aggressively to harmless substances, leading to inflammation, rashes, or more severe responses.

Medical conditions that may cause hypersensitivity reactions include:

• Asthma
• Allergic rhinitis (hay fever)
• Eczema (atopic dermatitis)
• Autoimmune diseases (e.g., lupus, rheumatoid arthritis)
• Drug allergies (e.g., penicillin allergy)
• Food allergies (e.g., nut or shellfish allergy)
• Contact dermatitis
• Serum sickness
• Inflammatory bowel disease (IBD)

What are the Symptoms of Hypersensitivity Reactions?

Hypersensitivity reactions often occur along with other signs that may help doctors identify the type and severity of the reaction. These related symptoms vary depending on the allergen and the body system involved.

Symptoms can differ based on the specific hypersensitivity reaction type and which part of the body is impacted.

Type I

• Sneezing,runny nose, and itchy eyes (hay fever)
• Hives and swelling (urticaria)
• Wheezing and shortness of breath (asthma)
• Anaphylaxis: severe, potentially life-threatening reaction causing difficulty breathing, low blood pressure, and loss of consciousness.

Type II

• Symptoms related to cell destruction include fatigue, weakness, and pale skin (hemolytic anemia).
• Fever and chills during or after a blood transfusion.

Type III

• Joint pain and swelling (rheumatoid arthritis).
• Skin rashes and organ dysfunction (SLE).

Type IV

• Red, itchy, and blistering skin rash (contact dermatitis).
• Skin irritations and organ impairment (SLE).

When to See a Doctor?

While some hypersensitivity reactions may be mild and manageable at home, others require medical attention. It’s important to know the warning signs that suggest a serious condition or the need for professional help.

Emergency Red Flags:

• Trouble breathing or chest tightness
• Swelling of the tongue or throat
• Drop in blood pressure or fainting
• Rapid heartbeat
• Confusion or bluish skin

Non-Urgent but Concerning Signs:

• Recurring skin rashes or persistent itching
• Frequent allergic reactions with no clear trigger
• Reactions that interfere with daily life
• Worsening symptoms despite avoiding allergens
• Use of antihistamines or inhalers more often than recommended

Hypersensitivity Reactions Diagnosis & Tests

Diagnosing hypersensitivity reactions involves identifying the trigger and determining the type of immune response involved.

Doctors start by reviewing your medical history, asking about symptoms, and conducting a physical exam to assess visible signs like rashes or swelling.

Depending on your condition, further tests are done to confirm the diagnosis and rule out other issues.

Physical Exams:

• Check for skin changes (rashes, hives, redness)
• Breathing assessment (wheezing, respiratory distress)
• General health check and history of allergen exposure

Lab Tests:

• Complete Blood Count (CBC): to check for elevated eosinophils
• IgE antibody test: measures allergic response
• RAST test (Radioallergosorbent test): identifies specific allergens

Skin Tests:

• Skin prick test: a small amount of allergen is applied to the skin to check for a reaction
• Patch test: used to detect contact dermatitis triggers

Specialized Diagnostics:

• Oral food challenge: supervised test for food allergies
• Pulmonary function tests: if asthma is suspected
• Drug allergy testing: for suspected medication reactions

What are the Treatments for Hypersensitivity Reactions?

Hypersensitivity reaction treatment varies based on the type and severity of the reaction:

• Avoidance: Identifying and avoiding allergens that trigger reactions.
• Medications:
• Antihistamines: For immediate relief of allergy symptoms.
• Corticosteroids: To reduce inflammation in more severe reactions.
• Bronchodilators: For asthma symptoms.
• Epinephrine: For emergency treatment of anaphylaxis.
• Immunotherapy: Allergy shots or sublingual tablets to gradually desensitize the immune system to specific allergens.
• Topical Treatments: Creams and ointments to relieve skin symptoms in contact dermatitis.

How can Hypersensitivity Reactions be prevented?

Hypersensitivity reactions can be prevented by avoiding known triggers, such as specific foods, medications, or environmental allergens. Here are some key prevention strategies:

• Identify and Avoid Triggers: Work with a healthcare provider to identify substances that cause reactions and avoid them whenever possible.
• Allergy Medications: Use antihistamines or other medications as prescribed by a doctor as a preventive measure if recommended.
• Immunotherapy: In some cases, allergy shots or sublingual immunotherapy can help reduce sensitivity to allergens over time.
• Environmental Control: Keep living spaces clean and use air purifiers to reduce exposure to environmental allergens, such as dust, mold, and pet dander.
• Medical Alert Identification: For individuals with severe allergies, wearing a medical alert bracelet can help in emergencies.
• Proper Medication Management: If medications are a known trigger, alternatives should be discussed with a healthcare professional.