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For most people, a sting means initial pain followed by localised swelling and itching. However, 2‒3% of the general population may be at risk of systemic hypersensitivity reactions to insect stings. Hypersensitivity reactions range from large localised swelling to sudden death from anaphylaxis.
You can be stung several times and think that you are not allergic, but the next sting may result in anaphylaxis. The body's response is to pump blood to the peripheral parts such as the arms and legs, and in severe cases the result is rather like a heart attack. Studies have shown that about 10% of people stung more than once become allergic to wasp venom.
A suspected anaphylactic reaction requires prompt medical treatment. A reaction that may initially seem mild, may progress to being more severe.
Severe anaphylactic reactions need immediate treatment with a medication called adrenaline, given in the form of an injection.The main action of adrenaline is to strengthen the force of the heart's contraction and to open up the airways in the lungs. Adrenaline is usually sufficient to reverse the reaction, though more than one dose may be required to achieve this. Other medications that may also be used to further reduce the allergic reaction include corticosteroids and antihistamines.
Self-injectable adrenaline kits (eg: EpiPen) are available. The injection device is filled with adrenaline and is administered into the large muscle in the front of the thigh when an anaphylactic reaction is experienced. The device holds only one dose, so medical assessment after the adrenaline has been administered is crucial in case the reaction worsens and further doses of adrenaline are required.
What to do if you or someone with you is stung:
- Apply a cold compress to relieve pain. Put ice in a cloth, plastic bag or plastic wrap. Don't put ice directly on the skin. Hold the cold compress on the site for 15-20 minutes.
- Take an antihistamine or apply antihistamine cream (available at a pharmacy) for the itching and swelling (unless you have to avoid these medicines for medical reasons). If you don't have a commercial antihistamine cream common household products are useful, e.g. for bee stings apply bicarbonate of soda, for wasp stings apply vinegar, on the affected area.
- Monitor the patient’s symptoms. If the patient's condition deteriorates, treat as for a severe allergic reaction. It is better to treat the patient early and maybe unnecessarily than wait until they are in anaphylaxis.
- If pain and swelling persist for a few days, seek medical aid.
If you have been stung in or near the mouth/throat:
- Seek medical advice as soon as possible
- Reducing the swelling — give ice to suck or rinse the mouth with cold water.
- Take an antihistamine or apply antihistamine cream (available at a pharmacy) for the itching and swelling (unless you have to avoid these medicines for medical reasons (talk to your pharmacist).
- If swelling continues, and casualty begins to cough or wheeze, treat as a severe allergic reaction.
Symptoms and signs of severe allergic reaction
Symptoms of a severe allergic reaction usually happen soon after or within an hour of the sting. These need to be dealt with immediately.
- Generally feeling "strange" or "off"
- Rapid pulse (>100 per minute)
- Fullness in throat
- Tightness in chest
- Hypotension (low blood pressure), patient feeling faint
- Stridor — raspy breathing
- Abdominal pain, cramps, diarrhoea or vomiting
- Feelings of impending doom
- Severe swelling, all over and/or of the face, tongue, lips
- Cardiac arrest
- Airway obstruction
- Respiratory arrest
- Keep the sting area lower than the level of the heart
- Administer emergency care as per instructions in wasp sting first aid kit — it is better to treat the patient early and maybe unnecessarily than wait until they are in anaphylaxis
- Monitor patient continually
- Seek medical help urgently
Wasp Sting First Aid Kit
Your first wasp sting aid kit should include:
- Self-injectable adrenaline (eg: EpiPen (a medicine that stops the body-wide reaction). Check expiry dates annually. Keep cool and out of the sun
- Antihistamine tablets
- Antihistamine cream
- An inhaler that contains Ventolin
- Instruction sheet that explains how to use the kit.
If you've ever had an allergic reaction to an insect sting in the past you should also wear a medic alert bracelet that lets others know you are allergic to insect stings. People who have had severe reactions in the past to bee or wasp stings should ask their doctor about immunotherapy (allergy shots).
Immunotherapy is also referred to as hyposensitisation or desensitisation. Treatment of increasing amounts of pure venom is usually administered once a week by subcutaneous injection until the equivalent of two stings can be tolerated. After that the patient must have monthly maintenance injections for several years.