Hives (Urticaria): Causes, Treatment and Prevention

Nationwide Children’s Hospital

Overview

Signs & Symptoms

Causes

Treatment

What to Expect

When to Seek Help

What Are Hives?

Hives are red, raised bumps on the skin that can be itchy. Hives are also called urticaria. About 1 in 5 people will get hives at some point in their lives.

What Are the Signs and Symptoms of Hives?

Hives can be found anywhere on the body. They can be small, like mosquito bites, or several inches wide. Even if they look different, hives often have common symptoms.

• People may have one hive or groups of hives that cover large areas of the body.
• Hives can move around on the body. They may start in one place, then move to another place on the body. 
• Hives may go away quickly or come and go for many weeks or months. 
• Skin swelling is common with hives. It may happen on the lips, ears, eyelids, fingers, or toes. This is common and not dangerous. 
• Less commonly, hives can occur as part of a more severe allergic reaction called anaphylaxis. Anaphylaxis can cause the airway to swell, making it hard to breathe. This is a life-threatening reaction that needs to be treated right away. 

What Causes Hives?

Hives happen when the body releases a chemical called histamine. It can be released because of allergies or other things, like stress, infections, or some illnesses. Whatever is causing histamine to be released is called a trigger.

• Hives not related to allergies are more common. Their triggers are:
  • Viruses or infections, like a cold, strep throat, or a urinary tract infection (UTI).
  • Emotional stress, like anxiety, anger, fear, or sadness.
  • Exercises that make the body warm.
  • Vibrations from using a lawn mower, horseback riding, or mountain biking.
  • Temperatures that are too hot or too cold.
  • Sunlight or tanning beds (sunlamps).
  • Pressure on the skin, like being rubbed too hard or scratched, or by wearing clothes that are too tight.

Hives that are related to allergies are less common. Their triggers are:

• Foods or medicines (anaphylaxis may occur) – Symptoms include nausea, throwing up (vomiting), mouth/throat swelling, and trouble breathing. This can be very dangerous.
  • Some common foods that cause allergies include eggs, peanuts, tree nuts, milk, and shellfish. 
  • Some medicines that cause allergies include aspirin, ibuprofen (Advil®, Motrin®), and naproxen sodium (Aleve®).
• Contact with the skin that can lead to irritation. These are usually not dangerous.
  • Plants, grasses, weeds
  • Acidic foods or sauces
  • Scents or fragrances (soaps, detergents, lotions)
  • Animal dander
  • Latex or other materials

When to Get Emergency Help

Call 911 or take your child to the closest emergency room if they have hives and any symptoms of anaphylaxis:

• Trouble breathing, swallowing, or talking
• Swelling of the mouth or tongue
• Nausea or vomiting

If they have an epinephrine auto-injector, like EpiPen®, Auvi-Q®, or Adrenaclick®, use it right away.

How Are Hives Treated?

Treatment depends on how bad the itching is. Even with treatment, hives can last days to weeks. The goals of treatment are to:

• Control the itching
• Avoid things that may trigger hives

For mild hives:

• Give an over-the-counter (OTC) antihistamine each day. Some examples are:
  • Loratadine (Claritin®)
  • Fexofenadine (Allegra®)
  • Cetirizine (Zyrtec®)
  • Levocetirizine (Xyzal®)
• Do not use Benadryl® creams. These may cause irritating rashes.
• Cool the skin using an ice pack or a cold bath or shower.
• Distract your child by playing games, singing songs, or reading books.
• Avoid known triggers, like animal dander or fragrance.

For severe hives:

• Give a higher dose of antihistamines or steroids, like prednisone. Oral steroids should not be used a lot. They may make hives worse when you stop taking the medicine.
• See a doctor or health care provider. They may prescribe a medicine, like Xolair® shots (injections), if you have long-term (chronic) hives.

Living With Hives

Living with hives isn’t easy, especially if you don’t know what’s causing them. It may help if you write down events that happened right before the hives appeared. This can help you and your child make a plan to keep the hives from coming back.

Depending on what’s causing your child’s hives, you can keep their hives from getting worse by having them:

• Avoid scratching or rubbing their skin.
• Wash their hands after touching pets or animals.
• Wear loose-fitting clothes. • Wear warm clothes. 
• Wear sunblock and long sleeves and pants in the sun.
• Avoid contact with cold water if they’re sensitive to cold.
• Use mild, unscented soap on their skin and for washing clothes.

When to Call the Doctor

Call the doctor or health care provider if your child’s hives get worse or prescribed medicine isn’t helping.

Hives (Urticaria) (PDF), Spanish (PDF), Somali (PDF)

HH-I-82 11/89, Revised 2023, Nationwide Children’s Hospital

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Itchy bumps on skin like mosquito bites: What are they?

Several skin conditions can cause itchy lumps that resemble bug bites. These include allergic reactions, infections, and chronic conditions.

Most people experience this symptom at some point. Itchy bumps can appear as a result of allergies, infections, insects, and, sometimes, nonidentified factors.

However, there is one general principle that the American College of Allergy, Asthma & Immunology recommend people to follow when their skin itches: Do not scratch it.

Additional general self-care practices for itchy skin include:

• bathing frequently in lukewarm water
• using gentle, hypoallergenic soap
• limiting exposure to the sun
• applying cold compresses
• avoiding tight clothing in areas where itchy bumps appear

Understanding the different conditions that can cause itchy bumps on the skin can help people get appropriate treatment. Depending on the cause, treatment can range from avoiding certain foods to taking prescription medications.

Keep reading to learn more about some common causes of itchy bumps that look like mosquito bites and how to treat them.

The medical term for hives is urticaria, and it describes a condition that produces raised itchy areas on the skin. If a person notices bumps on the skin that resemble mosquito bites but has not had any exposure to mosquitos, the cause is probably acute urticaria. The term “acute” means that the condition does not last longer than 6 weeks.

Hives are very common, affecting about 20% of people at some point in their lives. Certain kinds of foods, such as peanuts, tree nuts, and seafood, cause hives in many people due to an allergic reaction. Latex, pollen, insects, various plants, and some medications, such as sulfa drugs or even aspirin, may also cause hives.

Hives cause characteristic red, purple, or skin colored itchy bumps that appear and disappear quickly anywhere on the body. These bumps typically turn white or disappear when a person presses them.

Treatment

The treatment for hives depends on the severity and cause of the rash, but it includes avoiding known triggers. People who are extremely allergic to a trigger — for example, peanuts or certain insects — may need to carry an epinephrine auto-injector, such as an Epipen. This device can stop a potentially life threatening reaction if a person has accidental contact with a known allergen.

Anti-itching lotions and over-the-counter (OTC) antihistamines can provide relief for mild symptoms, while more intense outbreaks may require stronger prescription versions of these drugs or corticosteroids.

Learn more about hives here.

According to the Centers for Disease Control and Prevention (CDC), bed bug bites can resemble bites from other bugs, although they can take as long as 2 weeks to materialize.

People who notice itchy bumps on the skin that resemble mosquito bites should check for:

• other signs of bed bugs
• bed bugs themselves on a mattress or sheet
• dead bed bugs
• blood spots on a mattress or sheet
• the characteristic musty smell associated with bed bugs

If the bites appear in a straight line, they are likely to be due to bed bugs. However, bed bug bugs can also appear in more random formations.

Treatment

Unless someone has a severe allergic reaction, experts recommend simple self-care practices to treat any bites. These include not scratching, applying OTC antiseptic ointments, and taking antihistamines.

Learn more about bed bugs here.

Contact dermatitis is essentially an allergic reaction that develops when a person’s skin comes into contact with something to which they are allergic, such as latex or certain metals or household products.

It can take 1–2 days for the reaction to develop and 2–3 weeks for symptoms to disappear. Contact dermatitis may hurt as much as it itches, and it may present with inflammation and blisters.

Treatment

Self-care with cold compresses, calamine lotion, and soothing baths can help provide relief.

Prescription medication, such as antihistamines and cortisone, may be necessary if the reaction is severe.

Working with healthcare professionals can help people identify their triggers, which can be complicated.

According to the American Academy of Allergy, Asthma & Immunology, there are more than 3,700 substances known to cause contact allergies. Avoiding triggers is a key part of managing contact dermatitis, along with thoroughly washing the affected area with soap and water after exposure happens.

Learn more about contact dermatitis here.

The human itch mite is responsible for scabies. This mite digs its way through the top layer of the skin and lays eggs. Its tunnels can sometimes be visible on the surface of the skin, where they appear as raised, crooked, skin colored lines. However, the most common symptom of scabies is itchy bumps on the skin. These are like mosquito bites, only smaller.

Sites of the body that this very itchy condition commonly affects include the wrists, the elbows, between the fingers, and behind the knees.

Treatment

Only a prescription lotion will treat scabies effectively, and individuals need to follow the application directions exactly. Anyone who has had extensive skin-to-skin contact with someone with scabies should also seek treatment.

It is very important that people with scabies thoroughly wash and dry all of their clothes, towels, sheets, bedding, and other household items. Other remedies for scabies may also help.

Learn more about scabies here.

Also known as atopic dermatitis, this common condition causes itchy, red, irritated skin that can sometimes develop bumps. In the long term, it can make the skin thicker, scaly, and flaky, as well as causing it to change color.

Scratching makes eczema worse and increases the risk of infection. Eczema occurs due to a combination of genetic and environmental factors, which prompt the immune system to overreact to certain triggers, such as laundry soap or sweating. It typically affects the face, elbows, knees, scalp, and backs of the hands.

Treatment

According to the National Eczema Association, treating eczema calls for a mix of self-care, OTC drugs, and prescription medications. People with eczema can identify and learn to manage or avoid triggers for their outbreaks.

Changing bathing practices and using moisturizer can also help. Prescription lotions, systemic medications, UVB light, and biologics can address more severe symptoms.

Learn more about the different types of eczema here.

Skin problems, such as itchy bumps on the skin similar to mosquito bites, can range from mild to severe.

Some issues, including bed bug bites, can be fleeting, while others, such as allergic reactions to certain foods, are signs of a permanent condition. However, most skin problems generally respond well to treatment.

If the symptoms do not improve with self-care practices, people should see a medical professional to determine what is causing the outbreak and how to treat it.

DIROFILARIOSIS-PARASITIC DISEASE

Published: 17.06.2015

The mosquito season has begun. And if you
have not yet felt the obsessive attention of little bloodsuckers in their own
apartment, then, once in nature, you will definitely encounter them. To such
the meeting does not hurt to prepare, especially if there are atypical reactions to
mosquito bites. In addition to the usual allergy to an insect bite (itching, swelling,
redness), symptoms of general malaise, pain at the bite site,
unpleasant and alarming “movements” under the skin. It might not be
other than dirofilariasis .

Dirofilariasis is more common in areas with a warm and humid climate:
southern Europe, the countries of the Balkan Peninsula, Turkey, Africa, India. In Russia, dirofilariasis was registered in the southern
regions: in the Krasnodar and Stavropol Territories, the republics of the Northern
Caucasus, Astrakhan, Volgograd, Rostov, Lipetsk, Voronezh
regions, as well as Primorsky and Khabarovsk territories. In recent years
the parasite spread in
more northern regions of Russia. In Belarus annually
3–7 cases of dirofilariasis are detected. The most common disease occurs in
Gomel region.

Dirofilariasis —
a rare type of helminthiasis, in which the parasite is introduced under the skin and migrates along
body. For this disease
characterized by slow development and a long chronic course, accompanied by
complications in the heart, liver and kidneys.

Pathogen – immature nematode
Dirofilaria repens (roundworm). The parasite has a filamentous body
light yellow in color, tapering towards both ends, their larvae, called dirofilariae,
have a length of 0.22-0.30 mm. The length of an adult female
17–20 cm, width – 0.3–0.7 cm. Males are slightly smaller – 7 cm and 0.45 cm, respectively.

Microfilariae vector are
mosquitoes of various types incl. and mosquitoes that live year-round in warm and
basements of apartment buildings. They fly into the ventilation
systems in apartments and feed on humans and pets. Thus,
if there is a sick dog or cat in a city apartment, the transmission of infestation
can be carried from them to the person.

Main sources
infestations for humans are dogs. The disease also occurs in
foxes, ferrets, cats. Infection of dogs and other carnivores occurs in
in the process of feeding on them mosquitoes infested with dirofilaria larvae. IN
within 3 months, the larvae develop in the subcutaneous fat and connective
animal tissues, shed twice and penetrate into the bloodstream. By circulatory
system, the larvae migrate to the heart and pulmonary artery, where after 3-4 months
reach sexual maturity and become capable of producing larvae. Female
Dirofilaria gives birth to up to 30,000 larvae every day. microfilariae,
circulating in the blood of infested animals are non-invasive and do not
pose an immediate danger to other animals or humans.

For further
development, these parasites must be ingested by mosquitoes. The period of development of the larva in a mosquito to the invasive stage is about 17 days.

A person is infected by the bite of a mosquito that carries
contain dirofilaria larvae. Infestation
people, as a rule, occurs during agricultural work or recreation on
nature, where there are affected animals and mosquito colonies. More often
this happens during the period of insect activity (May-September). Increasing quantity
identified invasions in humans in recent years due to the growth of vagrant
animals, their mass migration between settlements, the process
urbanization, climate warming. All of these factors contribute to the transmission
parasite from wild animals to domestic and human.

Usually in the human body parasitizes one
helminth.

In rare cases, 2-3 helminths parasitize humans,
which, apparently, is associated with repeated cases of infection. In humans
the female helminth grows into an adult, but the “children” – dirofilaria –
does not give birth, therefore this disease is from a person
not transmitted to humans. Once in the body, the parasite reaches
largest in six months and is located under the skin (mucosa
shell), where a capsule of connective tissue is formed around it. IN
further the female gradually dies and collapses. The parasite is very
active: moves in the body at a speed of 10–30 cm per day. Clinical
symptoms

From
from the moment of infection until the manifestation of the main typical clinical symptom (movement of the pathogen, or
seals with it) passes from 1 month
up to several years.

Dirofilariasis manifests itself by migration through the body
parasite.

Later
a few days at the site of a mosquito bite, a small dense formation appears,
which may be accompanied by itching. Then it gradually increases
reaching a diameter of up to four centimeters. There is slight redness and
swelling of the skin over it, increased itching and pain. With the development of inflammation, the nodule
softens, suppurates, an abscess may form, on top of which
a hole appears from which the end of the worm protrudes.

When the parasite moves to its old place of residence, no
no traces remain, and a seal appears in the new area. There are symptoms of general intoxication: weakness, malaise,
headache, nausea, fever. An important symptom is migratory on palpation.
the knot is very mobile. Such a nodule persists for 2-3 months and periodically
disappears. All these sensations are present until the helminth around
a capsule will form.

Cases of localization of dirofilarial nodules in the area
head, neck, abdomen, popliteal region, thigh and other places.

Almost half of the cases of dirofilariasis involve
in the pathological process of the organs of vision.
Eye damage may be the only manifestation of the disease.
Helminths are localized and migrate in the subcutaneous tissue of the eyelid or under
conjunctiva. A knot (granuloma) is formed around the helminth, edema develops.
With the localization of the helminth in the subcutaneous tissue of the eyelids, a limited
tumor-like swelling, as a rule, with mild inflammatory
phenomena. The presence of the parasite under the conjunctiva causes phenomena
conjunctivitis. The disease can lead to severe hyperemia of the conjunctiva,
significant tearing. With the development of a granuloma in the orbit, pain is noted,
edema, erythema, exophthalmos, diplopia. Human can
completely lose sight.

Usually patients do not attach importance to the strange “pimple”.
After 1-3 months, when they begin to feel movement in that area or if
infiltrate appears on the face, they seek medical help.

Diagnostics. Specific
there is no diagnosis of dirofilaria detection. One of the diagnostic symptoms: the presence
feeling that a living thing is moving or crawling inside a dense formation
creature.

The final diagnosis is established only after the removal of the helminth, followed by parasitological
morphological research.

Treatment. Treatment of heartworm disease in humans
surgical and consists in removing the helminth.

Prevention

1. Personal measures
   prevention – protection against mosquito bites .
2. Combat
   mosquitoes in residential buildings, underground houses and other places.
3. Identification and
   treatment of invasive dogs, cats.

Why does a mosquito bite itch?

• Main
• All about allergies
• Allergy manifestations
• Why does a mosquito bite itch?

Contents

Why does a mosquito inject saliva into the victim’s body?

Itching at the site of a mosquito bite is the body’s reaction to the saliva that the mosquito injects into the skin.

When it bites, it pierces the skin with a special proboscis. At the same time, through one of its tubes, which is called the large lip, the mosquito feeds, that is, it drinks blood, and through the other – the hypopharynx, it injects saliva.

Saliva contains an anticoagulant – that is, a substance that prevents blood from clotting. If the blood clots around the mosquito’s mouth, it can get stuck in the host’s body and not fly up after it finishes eating.

In addition to anticoagulants, mosquito saliva contains 19 other enzymes and proteins. They are foreign to our body. Therefore, when they get inside, the immune system reacts to them as a threat. What happens next, according to classical ideas, resembles an allergic reaction.

How itching develops

According to some scientists, sensitivity to mosquito bites occurs in humans after they have been bitten for the first time. Due to such sensitization, in the future, with each bite, the body secretes special immunoglobulins, which lead to the destruction of the mast cells of the immune system. On the one hand, they help to heal wounds and protect against pathogens, but on the other hand, they release histamine. The release of this substance causes itching.

However, today there are new studies that suggest that in fact the whole mechanism of reaction to mosquito bites may be somewhat more complicated and does not depend on mast cells and histamine or depends not only on them. It is assumed that substances other than histamines are released, which then cause peripheral neurons to signal to the central nervous system. It interprets these signals and sends the information to the brain so that the brain lets you know that the mosquito bite is itchy.

By the way, only female mosquitoes bite. The fact is that the blood contains the nutrients that they need to lay eggs. Males do not need to do this, so they do not bite either people or animals. They feed on plant sap.

How itches at the site of a bite

Some people have only a mild reaction to a mosquito bite or bites. Other people react more strongly. Consequently, a large area of ​​edema, soreness and redness may occur at the puncture site.

Signs of a reaction to a mosquito bite include:

• swollen red bump that appeared a few minutes after the bite,
• hard, itchy, reddish-brown bump or bumps that appear about a day after the bite or bites,
• dark spots that look like bruises.

However, in children and adults who have been bitten by mosquitoes in the past, and in people with weakened immune systems, the reaction may be more severe. Also, a mosquito bite on the inside of the forearm is more difficult to tolerate.

In these cases, the person may experience:

• a significant swollen area at the bite site,
• elevated body temperature,
• urticaria,
• swollen lymph nodes.

Mosquito bite anaphylaxis

Some people develop a very severe allergic reaction to mosquito bites. In them, a bite can cause anaphylactic shock. Its symptoms are:

• breathing problems
• laryngeal edema
• swelling of the face
• urticaria
• weakness
• loss of consciousness.

If a person develops anaphylactic shock, they need emergency medical attention. Usually this is an injection of adrenaline, in particular, with the help of auto-injectors.

Bite Site Care

In general, redness and swelling at the site of a mosquito bite can last from several hours to several days. Each person reacts to mosquito bites in their own way. The main thing is not to comb or scratch the bite site, because this can lead to longer wound healing and even infection.

Mosquito bites sometimes leave small dark marks long after the itching and the bite itself have disappeared. As a rule, they occur in people with sensitive skin. However, these traces must pass. To avoid hyperpigmentation at the site of a mosquito bite, creams with vitamins C, E or niacinamide can be applied.

Prevention

The best way to prevent mosquito bites is to prevent them. But here it is important to know what exactly needs to be avoided, and what, on the contrary, can scare away these insects.

To protect yourself from bites, treat clothing with anti-mosquito solutions or sprays, wear long-sleeved shirts and long trousers.

Try to shower or use antiperspirant. Sweat and body odor attract mosquitoes.

Alcohol consumption has also been found to be associated with a greater chance of being bitten.

If you live in a private home, to reduce the number of mosquitoes, get rid of standing water, open sewers, empty the children’s pools at least once a week, change the water in the birdbaths at least once a week, get rid of old tires and empty them regularly flower pots or store them upside down…

When traveling to other countries, be aware that mosquitoes can carry diseases such as West Nile, Dengue, filaria parasitic worms, malaria, and others.