Insect bites and stings

General information

Insect bites are usually not dangerous to human beings, but some may produce an allergic reaction. An insect bite can also become infected. The bite is often red and it may develop a swollen lump. There may also be a tiny spot of blood at the centre of the bite.

Mosquitoes, black flies, sand flies, horseflies and deer flies

A mosquito bite develops a raised lump which clears up of its own accord in a couple of hours. If you are allergic or sensitive to mosquito bites, you may develop itchy nettle rash that may last for several days up to a week. You may even have blisters.

The black fly bite leaves a small bloody spot with a red and raised area developing around it. The bites burn and itch badly and scratching them will easily make them infected. Black flies and sand flies also find their way under your clothes to bite. Allergies to black fly and sand fly bites are rare. Black flies can spread tularaemia. Mosquito repellents do not protect against black flies or sand flies.

The reaction of the bite of the horsefly often includes nettle rash and localized swelling. The swelling may spread widely, even to a whole limb. The horsefly can spread tularaemia and in very rare cases borreliosis.

Deer flies aim for the scalp and underneath clothing. The bites are small red lumps that can seep pus. The bites may last for weeks, even months.

Self-care

You can take oral antihistamines or treat the skin area with hydrocortisone cream or products that contain antihistamine. If your insect bite or sting becomes infected, you can use topical antimicrobial cream available in pharmacies. The pharmacy staff will help you choose the right product. You can also reduce itching and pain with cold dressings or cooling gels.

If you are known to have had severe allergic reactions to insect bites before, it is important to prevent anaphylaxis by avoiding exposure to the allergen and by keeping an adrenalin injection (Jext or EpiPen) with you at all times, if you have been prescribed one.

The adrenalin in the automatic injector (Jext or EpiPen) should be administered immediately into the thigh or arm muscle as instructed on the package. There is no danger in using the adrenalin injection even if you don’t need one, and the only effect is a fast heart rate for the next twenty minutes. A second dose of adrenalin may be administered after 20 minutes, if necessary. It is highly recommended that you always carry two adrenalin injectors with you. The treatment can be supplemented with a bronchodilator, antihistamine and cortisone tablets.. (Terveyskirjasto).

You are also advised to carry your SOS-card on you at all times, where your allergies are listed and explained.

Wasps, bees and bumblebees

Wasp and bee stings leave a painful red and swollen area on the skin as a reaction to poison. If you are allergic to wasp or bee stings, you may experience more severe swelling and nettle rash that may spread widely on the skin if your reaction is severe.

The stings may also lead to a life-threatening anaphylactic reaction (low blood pressure, nausea and even loss of consciousness). Your response to new stings in the future may be unpredictable. People allergic to wasps are not usually allergic to bee poison and vice versa. Allergy to bumblebees is very rare.

Self-care

You can take oral antihistamines or cortisone tablets for an allergic reaction. Press the affected skin area with a cold dressing or cold pack and keep the area immobile so that the poison does not travel to a wider area. If you can see the sting, you can remove it to stop the poison from being fully absorbed. Mosquito repellents do not protect against wasps or bees.

If you have had severe allergic reactions to insect bites in the past, it is important to prevent anaphylaxis by avoiding exposure to the allergen and by keeping an adrenalin injection (Jext or EpiPen) on your person, if you have been prescribed one.

The adrenalin in the autoinjector (Jext or EpiPen) should be administered immediately into the thigh or arm muscle as instructed on the package. There is no danger in using the adrenalin injection even if you don’t need one, and the only effect is a fast heart rate for the next twenty minutes. A second dose of adrenalin may be administered after 20 minutes, if necessary. It is highly recommended that you always carry two adrenalin injectors with you. The treatment can be supplemented with a bronchodilator, antihistamine and cortisone tablets. (Terveyskirjasto).

You are also advised to carry an SOS card on you at all times, where your allergies have been listed and explained.

When should you seek medical advice?

You should call 112 in case of an insect bite or sting if

  • the patient has difficulty breathing or swelling in the throat or face
  • the patient has several stings near the face or neck.

Seek medical advice if

  • the patient has a single bite or sting in the mouth or neck area
  • there are several stings or bites in places other than the face or neck
  • the patient is a young child or an elderly person

If you suspect that the bite is made by an adder, contact health-care professionals immediately.

This Self-care instruction has been produced in collaboration with Duodecim Terveyskirjasto

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Updated  8.6.2020