What is Impetigo Herpetiformis?

Do You Have Symptoms of the Rare Pregnancy Rash?

woman looking at a pustule on her shoulder
What is impetigo herpetiformis?. Credit: Media for Medical / Contributor / Getty Images

Impetigo Herpetiformis - Definition

Impetigo Herpetiformis is a rare condition that has been reported in less than 100 pregnant women. The disease is similar to a type of psoriasis called pustular psoriasis, although women with impetigo herpetiformis usually have no personal or family history of psoriasis. Doctors disagree about whether it is a distinct disease caused by pregnancy or a form of pustular psoriasis triggered by pregnancy.

Despite the name "herpetiformis" the rash is not caused by a herpes virus. It is named "herpetiformis" based on the appearance of the pustules, which can look like those caused by herpes viruses (such as chickenpox.)

Impetigo herpetiformis is unrelated to a similarly named condition called dermatitis herpetiformis, a rash which has been coined the "celiac rash."

What Impetigo Herpetiformis Looks Like

The rash begins as pus-filled bumps, or pustules, on the edges of a red area of skin on the inner thighs and groin. The pustules join and spread to the trunk and extremities, usually sparing the face, hands, and feet. However, the rash can spread to the mucous membranes in the mouth and the nail beds. Even though pus is present, these lesions are not infected with bacteria, although they can become infected in the course of the disease.

When Does the Rash Occur in Pregnancy and Who is at Risk?

Impetigo herpetiformis typically begins in the last trimester of pregnancy.

The rash usually resolves after delivery but can recur in subsequent pregnancies. Women who have a parathyroid disorder called hypoparathyroidism may be susceptible to this condition during pregnancy as calcium and albumin levels in the blood fall. It's also currently thought that women with certain gene mutations may be at a greater risk of developing the rash.

It's not known how exactly why the rash occurs during pregnancy but not at other times. We do know, however, that there are many skin changes which normally occur in pregnancy.

Associated Symptoms with Impetigo Herpetiformis

Impetigo herpetiformis is frequently accompanied by significant symptoms such as fever, chills, nausea, vomiting, diarrhea, and fatigue. Some women experience low levels of calcium and phosphate in the blood. As noted above, women with hypoparathyroidism may be at risk of this condition.

How Impetigo Herpetiformis is Diagnosed?

Impetigo herpetiformis is usually diagnosed clinically by observing the symptoms and characteristic rash. A skin biopsy is typically performed to rule out other pregnancy-related conditions. Some studies have linked the condition to genetic mutations so it is possible that some physicians may order genetic testing.

What Else Could it Be?

There are many types of rashes that can be seen in pregnancy. A fairly common rash called pruritic urticarial papules and plaques in pregnancy (PUPPS) occurs in 1 out of every 160 women during pregnancy.

Similar to impetigo herpetiformis, this rash most often occurs in the 3rd trimester of pregnancy, but in contrast, tends to be very itchy.

Treatment for Impetigo Herpetiformis

Impetigo herpetiformis is treated with the oral steroid, prednisone. The beginning dose is usually fairly high and then tapered very slowly once symptoms are under control. Sometimes steroids are not well tolerated. If this is the case then other medications may be used. Antibiotics are only used if the rash becomes secondarily infected. Blood levels of calcium, phosphate, and albumin are monitored throughout the course of the disease.

Other treatments are currently being evaluated including

What Effect Can Impetigo Herpetiformis Have on Baby

According to the published work, impetigo herpetiformis is associated with the risk of stillbirth and placental insufficiency. Early recognition is important to reduce both maternal and fetal morbidity. Women with this condition should be closely monitored by a team of physicians to include dermatologists, obstetricians, and pediatricians.


Patsatsi, A., Theodoridis, T., Vavilis, D. et al. Cyclosporine in the Management of Impetigo Herpetiformis: A Case Report and Review of the Literature. Case Reports in Dermatology. 2013. 5(1):99-104.

Sugiura, K., Oiso, N., Linuma, S. et al. IL36RN Mutations Underlie Impetigo Herpetiformis. Journal of Investigational Dermatology. 2014. 134(9):2472-4.

Ulubay, M., Keskin, U., Fidan, U. et al. Case Report of a Rare Dermatosis in Pregnancy: Impetigo Herpetiformis. Journal of Obstetric and Gynaecologic Research. 2015. 41(2):3-1-3.

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