From mosquitos to midges, everything you need to know about treating and preventing insect bites and stings.
By Annie Hayes and Medically reviewed by Dr Roger Henderson
Insect bites and stings are the scourge of the summer. No matter whether you’re in Scotland or St. Tropez, once the weather heats up, it pays to be prepared – or you risk getting bitten or stung. Not only are insect bites and stings uncomfortable, unsightly and itch like mad, but if you’re allergic or the area gets infected, they can have some potentially severe side effects.
We spoke to pharmacist Navid Sole from Peter’s Pharmacy and Dr Deborah Lee from Dr Fox Online Pharmacy about how to identify, treat, and ultimately prevent bites and stings from occurring – plus, the symptoms of a bad reaction, and when to consider seeing a doctor:
What causes a reaction to insect bites or stings?
The most common insect bites in the UK are mosquitoes, midges, fleas, bedbugs, horseflies and ticks. Wasp and bee stings are acutely painful so you will usually know when you’re being stung. It can be difficult to identify what you were bitten or stung by if you didn’t see it happen.
For most people, an insect bite or sting usually causes a small red lump on the skin, which is often painful and can be extremely itchy. The question is: why?
‘When the insect clamps its jaws on the skin, it injects a small amount of saliva,’ says Dr Lee. ‘Your body may not have met this foreign substance before, and your immune system is called to action. As a result, within 24-hours of being bitten, the area becomes red, hot, and swollen.’
When the insect clamps its jaws on the skin, it injects a small amount of saliva.
While unpleasant, most bites or stings from insects found in the UK are harmless, says Sole. ‘While they may cause slight discomfort, they are usually not serious and will get better within a few hours. However, if you are allergic or the area gets infected it can have some severe side effects.’
Insect bites and stings symptoms
The longer the insect bites you, the greater your chance of an immune response. Most insect bites and stings are not serious and can be safely treated at home, but occasionally they can become infected, cause a severe allergic reaction, and even spread serious illnesses, including Lyme disease and malaria.
Your symptoms from a bite or sting reaction depend on how severely the bite or sting has affected you, says Dr Lee. Reactions span from minor – an itchy, red bump – to anaphylaxis, which is a life-threatening emergency:
- Minor reaction
Most people have experienced a bite like this before. ‘You may have just a few small red bumps which feel a bit itchy,’ says Dr Lee. ‘Sometimes bites can cause larger areas of redness and swelling. You can often see the bite mark in the centre.’
- Local allergic reaction
Bites sometimes cause a local allergic skin reaction called urticaria, also known as hives. ‘The allergic reaction results in histamine release into your skin,’ says Dr Lee. ‘Histamine is an important cell-signalling molecule involved in the immune response. Once histamine is present, it causes inflammation, and you can see a red, itchy skin rash with visible wheals (welts) at the site of the bite. This can be very irritating, but is not usually serious.’
- Large local reaction
Sometimes, the redness and swelling can measure more than 30cm in diameter, says Dr Lee. ‘If you have several bites, this can even result in swelling of your whole limb,’ she says. ‘In this case your symptoms will be more severe, with marked discomfort, and intense itching.’
- Systemic allergic reaction
If the allergy is more severe it can involve other systems of the body, hence it’s called a ‘systemic’ reaction. If there are toxins involved – for example, in a sting – it can cause a variety of symptoms such as cardiac arrhythmias, kidney problems, neurological symptoms, and abdominal pain, says Dr Lee.
‘A severe allergic reaction results in a large amount of tissue swelling, known as angio-oedema,’ she continues. ‘This occurs because fluid leaks out of small blood vessels and collects in the tissues. This swelling may just be localised to the affected area of the bite.’
This is an extremely serious systemic reaction. It occurs in up to three per cent of the population, and can be fatal, says Dr Lee. If the swelling associated with a systemic allergic reaction occurs in your mouth, throat, and airway, it can obstruct your breathing. ‘This is called anaphylaxis – or anaphylactic shock – and is a life-threatening medical emergency,’ she says. It usually develops rapidly, within minutes of the sting occurring.
Not all insect bites and stings look alike; they have different sizes, shapes and patterns.
Bee, wasp and hornet stings
When you’re stung by a bee, wasp or hornet, it causes a sharp and sudden pain or burning sensation at the site. Shortly afterwards, a swollen, red mark will arise, and this can last several hours and may be painful and itchy. This is likely to develop into a raised welt with a tiny white mark in the centre, where the stinger punctured your skin. The pain and swelling typically subsides within several hours.
When a bee stings you, the stinger may be left in the wound and will need to be removed as soon as possible due to the venomous toxins in it. Use something with a hard edge, such as a bank card, to scrape it out sideways. Don’t pinch the sting with your fingers (or tweezers) because you may spread the venom.
A horsefly bite can be incredibly painful, causing a sharp, burning sensation. The bite is more of an incision than a puncture, due to its scissor-shaped mandible – jaw, essentially – which cuts right into the skin. The mandible has hooks that allow the horsefly to latch on and feed on blood.
Horsefly bites can develop into large, red, itchy, swollen bumps within minutes. Itchiness, inflammation and swelling around the bite area is common, and you may even develop a bruise. Horsefly bites can take a while to heal and can become infected.
When a mosquito bites you, it injects saliva into your skin which acts as an anaesthetic and prevents your blood from clotting. For this reason, you might not realise a bite has occurred until later. It causes a round, swollen, itchy bump, sometimes with a small dot at the very centre. After a while, the bump becomes red and hard, sometimes swelling further. It’s not uncommon to get multiple bites around the same time.
While most tick bites are painless, they can be deadly. Unlike other insects, ticks can remain attached to your body for up to two weeks. They choose a place to feed – usually warm, moist or hairy areas – and bury their head into your skin. Since they are small in size, you may not notice a tick until they become engorged with blood and expand.
The most important thing to do when you find a tick on you is to remove it. You may be left with a small red bump, redness, swelling and itchiness around the bite area, with occasional blistering or bruising. Read our guide to safely removing tick bites.
Midge or gnat bite
Midge and gnats use scissor-like mouth structures to slice the skin open. Their painful bites often look remarkably similar to mosquito bites. Typically, they cause bumps that are small, red, painful, very itchy and potentially very swollen, too. In some people, the bumps turn into blisters filled with fluid.
Bedbug bites typically occur on areas exposed during sleeping, and usually in clusters or straight lines across the skin. They aren’t painful, since bed bug saliva contains an anesthetic, like that of mosquitos. Some people don’t develop noticeable symptoms from bedbug bites but when symptoms do develop, the bites tend to be red, swollen and itchy, with a dark spot at the centre. Occasionally the bumps turn into blisters filled with fluid.
The term ‘mite’ refers to a number of different organisms that belong to the arthropod family. They’re small in size and lack wings and eyes. Bites are often hard to identify. You might not feel the bite until after it happens or notice the mite when it bites, and the symptoms vary depending which type of mite bit you. Generally speaking, you can expect to see red, rash-like marks and itchy red lumps near the site of the bite. You may also have swollen or blistered skin. Some mites burrow into the skin and cause scabies.
Fleas are small, thin, flat bugs with no wings. Their bites look like small, red bumps that are often grouped in clusters of three or four or a straight line, and are very itchy. The skin around the bite may be sore or painful, and potentially could develop a rash. Fleas from cats or dogs commonly bite below the knee around the ankles, or on forearms if you have been holding or carrying your pet. Occasionally, blisters can develop too.
In the UK, spider bites are fairly uncommon, since few spiders have fangs long enough to puncture the skin. However, there are a handful of species – such as the false widow spider – that can cause inflammation and a necrotic wound if they bite. Spider bites leave small puncture marks on the skin, and can cause redness, pain and swelling like any other insect bite.
Ant stings and bites
The most common ant in the UK, the black garden variety, does not sting or bite. However, red ants, wood ants, and flying ants do sting occasionally, though they’re usually harmless. In some cases, the area may become itchy, swollen or painful. However, as with any bite or sting, there is the danger of infection setting in if you scratch it too much.
Flower bug bites
Flower bugs are predatory insects that feed mainly on aphids and mites, but they’re known to bite humans. Their bites can be painful and very itchy. They often take a while to heal.
Chiggers are the juvenile form of a species of mite that belongs to the Trombiculidae family. They are more common in America than the UK but can feed on skin cells. After being bitten, most people develop reddish welts within 24 hours of being bitten as the skin starts to harden around the bite area, followed by intense itching. The skin can resemble blisters, hives, pimples or welts, and and tend to appear in groups, typically increasing in size over the week following the bite. The itching may last for a week or longer if not treated.
Signs of a bad reaction to insect bites and stings
If any of the following symptoms occur, call 999 or seek professional help.
Symptoms to a bad reaction to a bite or sting include:
- Severe swelling
- Feeling nauseous
- A fast heart rate
- Difficulty swallowing
- Losing consciousness
Furthermore, some bites and stings don’t present symptoms immediately, says Sole, so if any of the following symptoms show after a couple of hours – or if symptoms don’t improve or get worse – then call your doctor.
Seek help if:
- A large area (around 10cm or more) becomes red or swollen.
- You start showing signs of a wound infection such as pus, severe pain, swelling or redness.
- You have symptoms of a widespread infection such as a fever, swollen glands and other flu-like symptoms.
‘If you have been bitten or stung and have any symptoms of an anaphylactic reaction, phone 999 immediately,’ says Dr Lee. ‘In most cases, insect bites and stings cause mild symptoms only and resolve by themselves in a day or two.’ If it’s not an emergency, but you are concerned about a bite, contact NHS 911 for advice or call into your local pharmacy.
How to treat insect bites and stings
Being bitten or stung is never pleasant, but you can make the recovery process more comfortable. Follow these tips for treating insect bites:
- Remove the sting
Take a good look at the bite or sting wound. ‘If this is a bee, a wasp, or a hornet sting, is the sting still present? If so, remove it carefully, using your fingernails, taking care not to get stung again,’ says Dr Lee. ‘Remove it whole without damaging the sting and unwittingly injecting more venom.’ If it’s a tick, wear gloves and use tweezers. ‘Grasp the tick near the skin and pull vertically upwards without twisting, so as not to leave the mouth parts in the skin,’ she says.
- Wash the affected area
Next, wash the area with soap and water and pat it dry carefully. ‘Apply a cold compress – such as an ice pack – to any swelling for at least 10 minutes, says Sole. ‘Raise or elevate the affected area to reduce swelling.’
- Don’t scratch
It’s going to take a lot of willpower, but scratching that itch won’t give you any relief in the long term. In fact, it’ll make it worse and leave you open to infection. Try not to touch the area unnecessarily, and consider a trip to the pharmacy if it becomes uncomfortable. ‘For itching, your pharmacist will be able to provide treatments including crotamiton cream, hydrocortisone cream and antihistamine tablets,’ says Sole. ‘For swelling, continue applying a cold compress, or go to your pharmacy to get some antihistamine tablets.’
- Take a painkiller
If the bite is painful, take paracetamol or ibuprofen, so long as there are no medical reasons you cannot take these medicines. ‘Lidocaine spray, a local anaesthetic spray for the skin, may be helpful,’ says Dr Lee. ‘If the area is very swollen, or the rash is extensive, sometimes a doctor may prescribe a short course of prednisolone (steroid) for you,’ says Dr Lee. ‘Steroids are very powerful anti-inflammatories, and safe to use in short courses.’
- Look out for signs of infection
Occasionally your insect bite will have started to heal, but a few days later it may be worse again. ‘Secondary bacterial infection can occur after a bite,’ says Dr Lee. ‘If you develop a temperature, start to feel generally unwell, and your local glands start to swell up, this may mean you need antibiotics. You may see pus in the wound. If so, see your doctor without delay. If there are blisters, do not prick them, as this encourages infection.’
- When to be concerned
If you have swelling or itching anywhere else on your body after being bitten or stung, or if you’re wheezing or have difficulty swallowing, you’ll need emergency medical treatment. Dial 999 for an ambulance.
How to prevent insect bites and stings
While there’s no guaranteed way to avoid the wrath of insects entirely, there are ways to prevent and reduce your risk of being stung or bitten:
✔️ Cover up
To minimise the opportunity for bites and stings, keep your arms and legs covered, with long-sleeved clothing and full length trousers. ‘Don’t walk around barefoot – keep your shoes on,’ says Dr Lee. You should also cover any food and drinks, remembering insects can climb inside cans. ‘Avoid rubbish bins and refuse areas and keep the lids on your bins,’ she continues. If you’re at home, keep windows and doors closed. ‘You can use a net covering at windows or a bead covering at doorways to stop insects getting into the house,’ says Dr Lee. ‘Keep your car windows closed.’
✔️ Invest in insect repellents
Use an insect repellent containing 50 per cent diethyltoluamide (DEET) in the summer months. ‘Apply your sunscreen first, then apply the insect repellent,’ says Dr Lee. ‘Spray the insect repellent on your hands and apply with your hands to your face. Don’t apply insect repellent under your clothes – just on exposed areas. Use just enough to cover the required area.’ Take care not to apply it to broken or inflamed skin, and wash your hands after applying.
✔️ Protect yourself at dusk
Insect bites are not inevitable if you take necessary precautions. The majority of biting insects come out at dusk, so this is when you need to be most vigilant. If you’re particularly prone or travelling somewhere warm, make sure your arms and legs are covered up during the evening and use mosquito nets when you sleep. The exception to the rule is the Aedes mosquito, which transmits the Zika virus and can strike at any time during the day, so take care if you are travelling abroad.