An insect bite often causes a small lump to develop, which is usually very itchy. A small hole (the actual bite) may also be visible. The lump may have an inflamed area around it that may be filled with fluid. This is called a weal.
Insect bites usually clear up within several days and can be safely treated at home.
Allergic reactions
Some people are particularly sensitive to certain insect bites and, when they are bitten, react badly to them.
However, severe allergic reactions to insect bites are rare. You are more likely to have an allergic reaction if you are stung by an insect. Never the less, it is still important to be aware of the symptoms of a severe allergic reaction, as it will require emergency treatment.
Symptoms of a severe allergic reaction may include:
- wheezing or difficulty breathing,
- severe itching, or a blotchy rash over many parts of your body,
- severe swelling which may be visible in your lips or tongue,
- dizziness,
- nausea, or
- chest pain.
Call 999 for immediate emergency medical assistance if, following an insect bite, or sting, you, or someone you know, is displaying these symptoms.
Symptoms of an infected bite
Sometimes insect bites can become infected. Symptoms of an infected insect bite may include:
- pus in, or around, the bite,
- swollen glands, or
- flu-like symptoms.
Another sign of an infected insect bite can be increasing redness, swelling, and pain in, and around, the bite. Some bites will naturally be red and swollen, but for other types of bite, these symptoms may be abnormal.
If you suspect that your bite may have become infected, or you are concerned in any way about your symptoms, you should see your GP, or call NHS Direct on 0845 46 47.
Sensitisation
If you are bitten by an insect, you may become 'sensitive' to its saliva. Being bitten again by the same, or a similar species, can provoke a local reaction to occur. For example, an itchy papule (lump), or an itchy weal (an inflamed, fluid-filled area) may develop, and last for several days.
The severity of the reaction will depend on your level of sensitivity. However, if you continue to be exposed to the insect's saliva (you continue to be bitten), you will eventually become immune to the saliva, and there will be no reaction at all.
Prognosis
Most insect bite reactions only last for a few hours and clear up quickly. However, occasionally, they can persist for several months. If you have a persistent infection following an insect bite, you may need to have follow-up treatment. You should seek advice from your GP about this.
In the case of tick bites, persistent reactions can occur, particularly if some of the insect's mouth parts are not removed from your skin. However, most tick bites heal within three weeks.
The symptoms that can occur from different types of insect bite are listed below.
Midges, mosquitoes, and gnats
Bites from midges, mosquitoes, and gnats often cause small papules (lumps) to form on your skin that are usually very itchy. If you are particularly sensitive to insect bites, bullae (blisters) or weals (circular, fluid-filled areas surrounding the bite) may develop.
Mosquito bites in certain areas of tropical countries can cause malaria.
Fleas
Fleabites can be grouped in lines, or clusters. If you are particularly sensitive to flea bites, they can lead to a condition known as papular urticaria (where lumps, or lesions, form). Bullae (fluid-filled blisters) may also sometimes develop. Cat and dog fleabites often occur below the knee, commonly around the ankles.
Horseflies
A bite from a horsefly can be very painful, and as well as the formation of a weal around the bite, you may experience:
- urticaria (a rash of weals),
- dizziness,
- weakness,
- wheezing, or
- angio-oedema (itchy, pale pink, or red, swellings that often occur around the eyes and lips for short periods of time).
As horseflies cut the skin when they bite (rather than pierce it), horsefly bites can take a long time to heal, and they can cause infection.
Bedbugs
Bites from bedbugs are not usually painful, and if you have not been bitten previously, you may not have any symptoms. However, if you are sensitised, you may develop intensely irritating weals (inflamed, fluid-filled area) or papules (lumps). Bites often occur on your face, neck, hands, and arms.
The Blandford fly
The Blandford fly (sometimes called blackfly) is found in east Anglia, Oxfordshire and Dorset.
Blandford fly bites are common during May and June, and are very painful, frequently occurring on the legs. They can produce a severe, localised reaction, with symptoms including oedema (itchy, pale pink, or red, swellings), blistering, fever, and joint pain.
Ticks
Ticks live in long grassy areas, and in forests where deer are found. Tick bites are not usually painful, and sometimes only cause a red papule (lump) to develop at the bite site.
However, ticks can carry a bacterial infection, called Borrelia burgdorferi, which causes Lyme disease. If Lyme disease is not treated, its effects can be serious (see the 'complications' section).
