What is a normal reaction to a wasp sting

Hundreds and thousands of people go to hospital emergency rooms (ER) or urgent care (UC) facilities seeking for medical help for insect stings every year, although most people are not allergic to insect stings.  Understanding sting insect allergies is important so people will be able to recognize the difference between a normal insect sting reaction and a severe, potentially life-threatening allergic reaction, will seek medical care accordingly, and reduce unnecessary anxieties, medical expenses, and medications. 

General Facts

It is estimated that up to 0.8% of children and 3% of adults may develop potentially life-threatening, severe systemic allergic reactions to insect stings. In the US, approximately 40 deaths each year in the United States are a direct result of stinging insect allergies. The sting insects that most commonly cause allergies in the United States include yellow jackets, hornets (yellow hornets and white-faced hornets), wasps, honey bees, and in the southern Unites States, fire ants.

Common Reaction Patterns and Symptoms

Recognizing the common patterns and associated symptoms after being stung by an insect will help you better understand what type of reaction you may be experiencing,  guide you on when to ask for help or seek care, and determine  the treatment you may need.

1. Normal reaction

• Also called local reaction, normal reaction is the most common reaction people encounter when they’re stung by a stinging insect.   
• Normal reaction includes pain, itching, swelling and redness confined to the sting site.

1. Large local reaction

• In addition to the local symptoms, swelling larger than 10cm in diameter is considered a large local reaction.
• People will notice an increase in size over the course of 24 to 48 hours.
• Symptoms typically take 3 to 10 days to disappear.

1. Systemic reaction

• A systemic reaction includes a range of different reactions and manifestations in the body, not limited to the site of the sting, with symptoms ranging from mild to life-threatening.
• Reactions affecting the skin such as hives, swelling, itching, flushing
• Bronchospasm, when your chest tightens and it becomes difficult to breath.
• Upper airway obstruction such as  tongue or throat swelling/closing
• Low blood pressure and cardiac shock
• Gastrointestinal including nausea, vomiting, or abdominal cramping

Key Takeaway #1

1. Most insect stings result in local reactions which are non-allergic and non-life threatening.
2. Although alarming in appearance, large local reactions are often treated the same way as normal reactions.  Only unusual painful or a very large local reaction may need medical attention.
3. Alternatively, any systemic reaction requires medical attention. 

Symptoms of a severe reaction:

Symptoms may include 2 or more of the following:

• Generalized itching or flushing
• Hives and swelling in the area other than the sting site
• Swelling of the tongue or throat
• Hoarseness or difficulty swallowing
• Chest tightness and difficulty breathing
• Abdominal cramping, vomiting, nausea or diarrhea
• Dizziness, fainting or a rapid drop in blood pressure
• Loss of consciousness or cardiac arrest

Key Takeaway #2

1. If you experience either one or a combination of the above symptoms after you get stung by a flying insect, it’s very likely that you’re developing an allergic reaction to the insect sting.
2. If you experienced such symptoms by a stinging insect in the past, you should know that you not only had an allergic reaction to the insect sting, but also carry a 60% higher risk of similar or worse reaction if stung again.  Therefore, you need to see an allergist, for further evaluation and management for your insect sting allergy.
3. A severe allergic reaction to an insect sting is a medical emergency; immediate medical attention is required.

Diagnosis: insect sting allergy testing pros and cons

Diagnosing an insect sting allergy is based on your detailed history of post sting symptoms and supportive allergy testing. Your allergist can then provide treatment options in the case of future stings.

• Prick and under the skin tests are the preferred method of insect sting allergy testing
• A serum sting insect specific immunoglobulin E (IgE) or radioallergosorbent test (RAST) can be used, but false-negative results occur in 15% of cases when testing with this alone. In order to confirm the diagnosis and if insect venom immunotherapy (allergy shots) is needed, a prick and intradermal skin test would still be necessary regardless of the RAST result.
• RAST, on the other hand, is indicated if there is a clear history of sting anaphylaxis but skin test results are negative.

Key Takeaways, Diagnostic Testing

1. Since false positive skin or RAST test results are present in more than 20% of healthy adults, insect sting allergy testing (skin or RAST) should not be used for general screening.
2. Normal, local, and large local reactions are not indicated for insect sting allergy testing.

Management and Treatment

Treating an insect sting allergy is divided into 2 important parts: preventive treatment measures for underlying allergy and symptomatic care when a sting occurs.

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