Papular Urticaria: A Guide to This Allergic Reaction

Medically Reviewed By Debra Sullivan, Ph.D., MSN, R.N., CNE, COI
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Papular urticaria is an allergic-type reaction to insect bites. It appears as itchy, red bumps that tend to cluster together. The reaction can persist for several days or even weeks. Another name for papular urticaria is persistent insect bite reaction.

This article explains papular urticaria and its symptoms, causes, and treatment.

What is papular urticaria?

Young person putting lotion on rash
Evgenij Yulkin/Stocksy United

Usually, the name can give clues to the meaning of medical terms. Papules are elevated lesions, and urticaria is another name for hives. However, papular urticaria is not the same as hives. Instead, it refers to an allergic-like reaction specific to insect bites. Essentially, people with this condition are highly sensitive to bug bites. 

Children are most likely to get papular urticaria. Their immune systems have not had as much exposure to insect bites as an adult’s immune system. Eventually, children become desensitized to the bites, and the reaction stops. However, this can sometimes take months or years. Less often, papular urticaria occurs in adults.

Papular urticaria can affect people at any time of year. However, it is more likely when insects are most active. Depending on the climate, this may occur in the spring, summer, or fall.

Several other conditions have similar names to papular urticaria, but they are not the same. Pruritic urticarial papules and plaques of pregnancy (PUPPP) is one such condition. PUPPP is a skin condition with an unknown cause that tends to occur in first-time pregnancies.

What are the symptoms of papular urticaria?

The main symptom of papular urticaria is a cluster of itchy, red bumps. The bumps usually appear on exposed body parts, such as the legs. However, they can occur anywhere. Blisters can also occur with the bumps.

Papular urticaria lesions can persist for several days or weeks. When they resolve, they can leave darkened scars that can last for many weeks. The name for this is postinflammatory hyperpigmentation. It is more likely to occur with deep or intense scratching.

The problem can recur, with old lesions becoming itchy again after new bites.

The symptoms of this condition are localized rather than systemic, meaning they are not present throughout the body.

What does papular urticaria look like?

A person's ankle showing with red bumps of papular urticaria
Papular urticaria is an allergic-like reaction to insect bites. It looks like a group of red, itchy bumps that form in a cluster or line. Roberto Binetti/Shutterstock

Papular urticaria looks like a group of red papules, which are elevated lesions. They can occur in clusters, lines, or curves.

The papules often have a punctum, which is a small, central point or tip. Fluid-filled blisters may accompany the papules.

What causes papular urticaria?

Papular urticaria is most likely an overreaction of the immune system. Insect bites trigger the reaction that is most common in children. As children age, their immune system becomes less sensitive to the bites, and the reaction subsides.

Any biting insect can cause papular urticaria, but fleas and mites are the most common culprits. Others include:

  • bed bugs
  • beetles
  • caterpillars
  • gnats
  • midges
  • mosquitos

Children may not remember receiving a bite. As such, it can be hard to identify the insect in some cases.

How do you prevent papular urticaria?

Preventing papular urticaria relies on avoiding bug bites. To prevent bug bites:

  • Apply insect repellant to exposed skin.
  • Eliminate insects from the home, using a professional exterminator if necessary.
  • Seek veterinary care for pets that can be insect carriers.
  • Wear protective clothing that covers the skin.

How do you diagnose papular urticaria?

Typically, papular urticaria is a clinical diagnosis. This means doctors rely on your medical history and an exam to make the diagnosis. Testing is usually not necessary. In some cases, doctors may take a skin biopsy to confirm the diagnosis.

How do you treat papular urticaria?

Papular urticaria is a self-limiting condition. Eventually, children outgrow the reaction as their immune systems become less sensitive. Treating the reaction itself is symptomatic.

Doctors may recommend the following to treat papular urticaria reactions:

  • oral antihistamines
  • topical corticosteroids 
  • unscented moisturizers

Use a daily sunscreen on old, darkened lesions to protect them from sun and help them fade quicker.

What are the potential complications of papular urticaria?

Secondary bacterial infections are a potential complication of papular urticaria. These infections can become serious, causing cellulitis in the area. In rare cases, sepsis can occur.

Avoid scratching as much as possible, and keep nails trimmed to minimize skin damage. If an infection develops, antibiotics may be necessary.

Frequently asked questions

Here are some other questions people often ask about papular urticaria.

How long does papular urticaria last? 

A papular urticaria reaction can last several days or even weeks. The reactions can continue and recur for months to years. Eventually, children tend to outgrow the reactions. Once their immune systems become less sensitive, the reactions should subside.

What is the difference between papular urticaria vs. scabies?

Scabies is a skin infestation with the mite, Sarcoptes scabiei. The mite burrows into the skin and lays its eggs. Papular urticaria is a reaction to an insect bite rather than a live insect inside the skin.

What is the difference between papular urticaria vs. pruritic urticarial papules and plaques?

Papular urticaria is an allergic reaction to insect bites. PUPPP is a condition that usually occurs in the third trimester of pregnancy. It is most common in first-time pregnancies. It consists of itchy, red lesions that often begin on stretch marks. The cause is unknown, and it generally does not recur in subsequent pregnancies.

Summary

Papular urticaria occurs in response to insect bites and resembles an allergic reaction. It most often affects children whose immune systems have not yet desensitized to bites. However, adults may also experience it.

Papular urticaria consists of itchy, red bumps appearing in clusters or crops. The reaction is self-limiting and typically resolves as children age and outgrow it. Treatment aims to relieve symptoms and prevent secondary bacterial infections.

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Medical Reviewer: Debra Sullivan, Ph.D., MSN, R.N., CNE, COI
Last Review Date: 2022 Sep 16
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
  1. Chouk, C., et al.(2021). Pruritic urticarial papules and plaques of pregnancy. https://www.ncbi.nlm.nih.gov/books/NBK539700/
  2. Cunliffe, T. (2021). Papular urticaria. https://www.pcds.org.uk/clinical-guidance/papular-urticaria
  3. Lara-Corrales, I., et al. (2017). What is papular urticaria? https://pedsderm.net/site/assets/files/1028/spd_papular_urticaria_color_web_final.pdf
  4. Oakley, A., et al. (2021). Papular urticaria. https://dermnetnz.org/topics/papular-urticaria
  5. Scabies FAQs. (2020). https://www.cdc.gov/parasites/scabies/gen_info/faqs.html