Mosquito bite symptoms – what is normal and what is not

Mosquito bites

The name ‘mosquito' comes from the Spanish word ‘little fly' but you should not be fooled by their appearance. Mosquitoes are small but lethal insects that usually inhabit warm, tropical countries and are infamous for their capacity to distribute mosquito bites and in doing so, spread deadly and dangerous diseases.

This is because female mosquitoes need to ingest blood in order to be able to reproduce properly - so male mosquitoes don't actually tend to do much of the mosquito biting. This makes these pesky female mosquitoes particularly fond of any warm-blooded human that stumbles into their midst and they usually attach themselves to any visible skin, where it sucks blood through a sharp, elongated mouthpiece known as a proboscis, (collecting it's blood meal) and then injects saliva, from themselves, into your bloodstream.

A mosquito only needs to be attached to your skin for six seconds in order to complete it's mosquito biting, collect it's blood meal and thereby produce a reaction from your immune system¹.  In most cases, despite their reputation for carrying disease, the most irritating symptoms will normally occur because of this immune reaction as your body will recognise the proteins in the mosquito saliva as being dangerous. This will then cause a number of symptoms to manifest around the bite mark itself, usually in the form of skin lesions and swelling and this is why mosquito bites itch too.

If you want to read more about the appearance of a mosquito bite, then please check out our blog, ‘What does a mosquito bite look like?' This can help to differentiate mosquito bites from other bug bites such as flea bites.

^{1. http://www.aaaai.org/conditions-and-treatments/library/allergy-library/taking-a-bite-out-of-mosquitoes}

Common mosquito bite symptoms

As we have mentioned, not all mosquito bites foreshadow deadly diseases like malaria or yellow fever, instead, it would be a rare occasion, being bitten by an infected mosquito. Often the main source of aggravation is the proteins contained in the saliva. These proteins can sometimes prevent your blood from clotting and prompt an inflammatory, immune reaction, triggering many of the common mosquito bite symptoms.

Discolouration

When you receive a mosquitoes bite, it will trigger a response from your immune system. Your immune system recognises the toxins in mosquito's saliva as being harmful and releases a wave of inflammatory chemicals to counterattack the invading pathogens.

These chemicals can sometimes stimulate the melanocytes, the cells responsible for producing the dark skin pigment melanin, causing small dark spots to appear around the affected area, possibly resembling bruising. Inflammatory chemicals like histamine also dilate your blood vessels, inspiring skin redness around the bite mark.

Lumps

When a mosquito bites you, your body will react within minutes. The primary symptom of a mosquito bite is often the pale, swollen lump that appears around the bite mark itself. This inflamed pustule is normally characterised by a small red dot in the centre of the affected area. Over a period of days, this lump can harden, with multiple puffy lesions appearing, depending on how many times you have been bitten

Inflammation

Inflammation is usually one of the first visible symptoms of a mosquito bite. In response to mosquito saliva entering your bloodstream, an immune response will try to protect your body and destroy the harmful pathogens.

In order to do this, inflammatory chemicals like histamine are directed to the affected area, causing your skin to redden and swell in an effort to remove the irritants and begin the healing process. Whilst itchy bites can be frustrating, try to avoid scratching as much as possible to help prevent against any further inflammation.

Itching can be one of the more aggravating symptoms of a mosquito bite. In terms of reactions to mosquito bites, this is quite a common scenario - some resultant, mild inflammation and skin irritation, however, it still could upset your sleep or leave you vulnerable to contracting a secondary bacterial infection if bacteria or other infections get into the bite site. This is because when you continuously scratch your skin, you are weakening the epidermal layer, disrupting the healing process and destroying healthy skin cells, making it easier for other pathogens and allergens to penetrate your skin. Scratching with dirty nails could also spread germs more easily.

Moderate mosquito bite symptoms

If you have weakened immunity, then sometimes more severe symptoms can present themselves. Children, for example, are more prone to developing these symptoms because their immune systems are not fully formed or able to build a resistance against the chemicals contained in mosquito saliva. This can cause a more severe allergic reaction, leading to more unpleasant symptoms developing.

However, if you have any doubts about any of the symptoms that you are experiencing at the hands of mosquito bites, you should always speak to your doctor just to confirm that what you are experiencing is normal and not a precursor to a more serious medical illness.

Blistering

Blistering is a more serious skin reaction to a mosquito bite, often appearing in those with a weakened immunity. Small, fluid filled pustules will start to appear around the bite mark, sometimes causing irritation and pain.

However, you should resist the urge to squeeze or pop any blisters as, similarly to scratching, it can slow down the healing process, weaken the skin and make you more susceptible to contracting a secondary bacterial infection

Hives

Hives are a common appearance in those that suffer from ‘skeeter syndrome' or have weakened immunity, hives are itchy red welts that can occur as a result of an allergic reaction, either to food, pollen or insect bites.

They are normally extremely irritating and can contribute to very itchy skin, but they are not known to have any long term effects, usually diminishing within six weeks or so of manifesting.

Swollen lymph nodes

Occasionally, when your body has a more extreme reaction to a mosquito bite, your lymph nodes or glands can become swollen and inflamed. This is mainly due to the role that your lymph glands play in helping the immune system to fight infections and pathogens.

In rare instances, swollen lymph glands can be a sign of a mosquito-borne illness like Dengue fever, but more often than not the symptom is found in children that have been bitten by a mosquito and usually it fades as the bite is treated or diminished.

Mild headaches

Having a mild headache is considered a moderate reaction to a mosquito bite, normally appearing in those who have a weakened immune system. You can experience slight pain or tension, but it is not usually persistent and can be relieved used conventional painkillers or home solutions.

If your headache intensifies or is prolonged, it might be a sign of a more serious illness and you should consult your doctor as soon as possible.

Low fever

A mild or low fever is a symptom that can sometimes occur, normally when the immune system is struggling to fight off an invasive pathogen. You might find that your temperature is slightly, but not alarmingly, higher than usual.

This symptom should begin to diminish within a few days but if it persists or worsens, you should speak to your doctor immediately as it might be a sign of a more serious, mosquito-borne illness.

Serious mosquito bite symptoms

While moderate mosquito bite symptoms are often a sign of a weakened immune system, serious mosquito symptoms like vomiting, diarrhoea and joint pain can indicate that you have contracted a mosquito-borne disease like malaria, zika virus or yellow fever.

If your condition is diagnosed quickly, it can be treated successfully with proper medication, however if you allow your symptoms to linger, you might be putting your health and your life at risk.

Anaphylaxis - a severe allergic reaction

A dangerous and potentially life-threatening condition, anaphylaxis usually appears in intense allergic reactions and can be characterised by dizziness, wheeziness and difficulty breathing.

A mosquito bite allergy could cause the blood vessels to swell abnormally, trigger anaphylactic shock within minutes of coming into contact with the perceived pathogen. If you are not treated quickly enough, it can be fatal.

Severe headache

A severe headache is classified as a persistent headache that causes potent amounts of pain. It can be sometimes be a symptom of mosquito-borne afflictions like as Zika virus or West Nile disease, so you should speak to your doctor just to confirm that you are not suffering from one of these conditions.

High fever

If your temperature is raised over 37oC you are considered to have a high temperature. If you start to develop flu like symptoms, your temperature could easily climb to over 38oC, but if it continues to climb higher, you can be at serious risk.

Fever is associated with many different mosquito-related diseases, like malaria, Skeeter syndrome and yellow fever. If you are in doubt, speak to your doctor as soon as possible to achieve a diagnosis and start any relevant treatment

Skin rash

A skin rash can occur as a symptom of chikungunya virus, a mosquito-borne disease that can affect your muscles and joints. Although skin reactions like inflammation and discolouration are commonplace after being bitten, if a rash continues to develop and shows no signs of diminishing, you should speak to your doctor just to clarify that what you are experiencing is normal and non-threatening.

Fatigue

If you are unused to hot, tropical climates then sometimes the increased temperatures and heat can make you feel lethargic, meaning that any symptoms of fatigue often gets overlooked by holidaymakers abroad.

However, fatigue can be a warning sign of dangerous afflictions like West Nile Virus or chikungunya virus. If you notice that you feel abnormally tired after being bitten, and suspected you are an infected person, then it might be worth visiting your doctor just to make sure that what you are feeling is not a precursor to a more serious condition.

Nausea

Feelings of nausea, like fatigue, can often be overlooked or misdiagnosed, either as food poisoning or heatstroke. If you've been bitten by a mosquito though, you should be aware that nausea is often a sign of diseases like chikungunya virus and should not be ignored.

If you manage to catch this illness is its early stages, you might be able to avoid some of the other unpleasant symptoms that can manifest alongside nausea.

Vomiting

Vomiting is never a good sign and should always be treated seriously. In cases of a mosquito bite, the affliction can precede more serious symptoms and even be an indicator that you are suffering from dangerous illnesses, such as malaria or dengue fever.

Diarrhoea

Diarrhoea can be unpleasant and embarrassing to experience but if you are on holiday, the chances are you would blame the affliction on food poisoning, dirty water or another ailment. However, if you've been bitten by a mosquito you should consider the idea that you might have contracted a more unfortunate disease. If you are unsure, you should visit your doctor just to put your mind at ease and confirm whether it is just an upset stomach or something more serious

Joint pain

Joint pain, muscle pain or body aches can be debilitating and is not a symptom that you might immediately associate with a mosquito bite. However, it is a leading side-effect of chikungunya virus and if left untreated it can even become chronic, lingering for months, if not years, after other symptoms have diminished. If you are uncertain about your joint pain, muscle pain or unusal body aches, you should speak to your doctor

Disorientation

If you are feeling disorientated, you might be tempted to blame heatstroke or dehydration. If you've been bitten by a mosquito though, it can herald an assortment of mosquito-borne viruses. Drink plenty of fluids and speak to a doctor so that you can determine exactly what is causing your confusion.

How to prevent mosquito bites

Whilst most mosquito bites are fairly mild, if you are worried about the possibility of mosquito bites and are keen to try and prevent mosquito bites in the first place, (rather than dealing with itching and all the symptoms that can crop up afterwards), then there are some preventative steps you can take.

A mosquito net can help to keep mozzies out, as well as other flying insects, for that matter. And whilst a net won't work if you're out and about during the day (although you can get face coverings), it could help to protect against multiple nights, come night time.

An insect repellent can also be applied to any exposed skin, day and night to help keep the bugs away. Stagnant or standing water such as children's wading pools can also attract bugs if left, so always clear away areas, and empty children's wading pools, or areas of standing water that might attract more insects.

In certain parts of the world, the risk of 'high risk bites' or the event of a more severe reaction as a result of a mosquito bite might be increased. Mosquitos which spread diseases tend to only exist in certain areas, which disease control authorities are usually aware of. You can check these more high-risk areas ahead of travel in order to help prevent malaria or similar more serious complications of mosquito bites.

What should I do if I’ve been bitten?

If you have been bitten by a mosquito, even if you are just suffering from mild, superficial symptoms, you might prefer to speak to a doctor - this would definitely be the best approach if you think you might have an infected bite. Mosquito bites are often a mild complaint but sometimes they can be deadly, and you might agree you don't want to take any chances with your health.

However, in some cases, home remedies such as applying a cold compress or an ice pack can be suitable, and could help to reduce some of the inflammation. Some people like to apply calamine lotion to help relieve itchy mosquito bites, or some other over-the counter remedies also exist such as an anti itch cream, which includes options such as a hydrocortisone cream, which can also help to relieve itching. Something stronger may be required if you have multiple bites to contend with or are really struggling to stop scratching - excessive scratching may only spread germs further.

If you are unsure about how to protect yourself from the little beasts, you can check out my ‘Top 10 tips to prevent mosquito bites' for more information or try using our Neem Insect Repellent Spray, which does not contain DEET. Instead, this spray utilises extracts of neem, making it a gentler option for sensitive skin without compromising on efficiency.

^{Originally published on 16/8/16, updated on 10/05/24}