Impetigo Herpetiformis Is a Rare Pregnancy Rash

woman looking at a pustule on her shoulder

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Impetigo herpetiformis is a rare condition that has been reported in fewer than 100 pregnant women. The disease is similar to a type of psoriasis that's 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 that's caused by pregnancy or a form of pustular psoriasis that's 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 that are caused by herpes viruses (such as chickenpox.) Impetigo herpetiformis is unrelated to a similarly named condition called dermatitis herpetiformis, a rash that has been coined the "celiac rash."

What It 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 of the mouth and the nail beds. Pus is present, but these lesions are not infected with bacteria, though they can become infected throughout the course of the disease.

Impetigo herpetiformis typically begins in the last trimester of pregnancy. The rash usually resolves after delivery but can recur in subsequent pregnancies.

Who Is at Risk

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 who have certain gene mutations may be at a greater risk of developing the rash.

It's not known why the rash occurs during pregnancy but not at other times. However, there are many skin changes that normally occur during pregnancy. 


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. 


Impetigo herpetiformis is usually diagnosed by its symptoms and its 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 (also known as PUPPP, PUPPS, or PEP) occurs in one out of every 160 pregnant women. Similar to impetigo herpetiformis, this rash most often occurs in the third trimester of pregnancy, but in contrast, it tends to be very itchy.


Impetigo herpetiformis is treated with the oral steroid prednisone. The beginning dose is usually fairly high and then it's 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 used only if the rash becomes secondarily infected. Blood levels of calcium, phosphate, and albumin are monitored throughout the course of the disease.

What Effect Can the Condition Have on Baby

According to research, 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.

So if you suspect that you may have impetigo herpetiformis, call your doctor right away. 

2 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Kondo RN, Araújo FM, Pereira AM, Lopes VC, Martins LM. Pustular psoriasis of pregnancy (impetigo herpetiformis)--case report. An Bras Dermatol. 2013;88(6 Suppl 1):186-9. doi:10.1590/abd1806-4841.20132134

  2. Taylor D, Pappo E, Aronson IK. Polymorphic eruption of pregnancy. Clin Dermatol. 2016;34(3):383-91. doi:10.1016/j.clindermatol.2016.02.011

Additional Reading

By Heather L. Brannon, MD
Heather L. Brannon, MD, is a family practice physician in Mauldin, South Carolina. She has been in practice for over 20 years.