Insect bites and stings

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Insect bites and stings


​Bites and stings of flying insects may cause skin symptoms and hypersensitivity reactions. The severity of reactions from bites and stings vary. Symptoms may be alleviated by self-care.

An insect bite or sting may often produce a reaction such as redness and may develop a swollen lump on the skin.  There may also be a tiny haematoma at the centre of the bite. In Finland, insect bites and stings are usually harmless to human beings.​


Mosquito bite

Most people are sensitive to mosquito bites. A mosquito bite may develop a raised nettle rash lump which clears up of its own in a couple of hours.  In a delayed reaction, an itchy bump may emerge in a couple of hours and last for several days. Serious allergic reactions to mosquito bites are rare. Finnish mosquitos may spread diseases, e.g. tularaemia. Use mosquito repellents to protect yourself against mosquitos. 

Black fly and midge bites

The black fly bite leaves a small haematoma with a red and slightly swollen area developing around it.  The midge bite, a couple of millimetres in size, may sting and burn painfully. Black flies and midges can easily bite also underneath clothing. Hypersensitivity to the bites is very rare. Black flies can spread tularaemia. 

Horse fly bite

A horsefly bites often cause a large swollen lump with a watery spot in the middle of it. The bite may cause allergic reactions like hives (urticaria) and extensive swelling. Also serious allergic reactions are possible. Horse flies can spread tularaemia.

Deer fly bites

Towards the end of summer and in autumn, deer flies populate the areas where elks herd. Deer flies aim for the scalp and underneath clothing. If you are sensitive to deer fly bites, you may develop small red lumps which may take weeks to heal. Deer flies do not spread disease to humans.

Wasp, bee and bumblebee bites

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 lumps similar to nettle rash. Skin symptoms may spread widely on the skin if your reaction is severe. 

Wasp and bee stings may also lead to a life-threatening anaphylactic reaction with low blood pressure, nausea and in the worst case even loss of consciousness. You may become sensitive to wasp and bee stings so that the reaction to new stings may be unpredictable. People allergic to wasps are not usually allergic to bee poison and vice versa. Allergic reactions to bumblebee stings are very rare. Mosquito repellents do not provide protection against wasps or bees.​​


Insect bites and stings self-care

Reactions from insect bites and stings may be alleviated by products you can get over the counter from pharmacies. You can relieve symptoms by oral antihistamines or apply cortisone or antihistamine cream on the skin. Pharmacy staff will help you select the right product, if necessary.

Itching and stinging can be alleviated with cold packs.​

Wasp and bee sting self-care

If you can see the sting, remove it immediately. Press the affected skin area with a cold compress or cold pack to relive the pain. Raise or elevate the affected area if possible, as this can help to stop the poison from travelling to a wider area. You can relieve the reaction from a wasp or bee sting by oral antihistamines or cortisone tablets.

Treatment and prevention of severe hypersensitivity reactions

You can take oral antihistamines or cortisone tablets for severe allergic reactions from insect bites or stings.  Hydrocortisone tablets can be bought over the counter from pharmacies (for instance Kyypakkaus® or Ampikyy®).

 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 injector (Jext or EpiPen) available, if you have been prescribed one. The adrenalin in the autoinjector 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 or so. 

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 seek medical advice, if

  • you have a single sting or bite in your mouth area or throat.
  • you have several stings or bites on your body (than the face or throat). 
  • self-care does not provide sufficient relief or your symptoms worsen.
  • an area around the bite or sting is infected (becomes red and swelling increases)

if, after the incident, you have difficulty breathing or have swelling in the throat or face or if you have several bites or stings in your face or throat area, call 112 immediately. 

More information

The producers of the instruction

​​​​​Emergency care professionals have produced the instruction in collaboration with Terveyskirjasto.​


Updated  1.5.2021