What Is Crusted Scabies?

Crusted scabies, also known as Norwegian scabies, is a severe form of scabies that typically happens in people with a weakened immune system.

Scabies mites are parasites that burrow into and lay their eggs in the upper layer of human skin. Scabies is treatable and not usually a cause for concern. However, in people who are immunocompromised, the infestation can become severe and difficult to treat. 

With crusted scabies, a person can be host to millions of mites, compared to a regular infestation, which usually involves 10 to 15 mites.

This article will provide an overview of crusted scabies, a severe form of scabies, including symptoms, causes, risk factors, treatment, and prevention.

Crusted Scabies Symptoms

Symptoms of crusted scabies are often similar to regular scabies but are more severe. Some people may only experience crusting without other symptoms, however. 

Symptoms may include:

• Intense itching that keeps you awake
• Hive-like bumps on the skin 
• Scaly, crusty rash 
• Sores 
  

People with crusted scabies will have very thick crusts on their skin because of the large number of mites present. In some people, intense itching can trigger scratching that causes an infection. 

Common spots for scabies infestations are:

• Arms
• Hands, especially between the fingers
• Buttocks
• Genitals
• Nipple area
• Waist area
• Skin covered by clothing or jewelry
  

If you have close contact with someone with scabies, you may not develop symptoms immediately. It can take up to eight weeks to notice symptoms if you’ve never had scabies before. If you’ve previously had scabies, symptoms may appear sooner.

Causes

Scabies happens when you come into direct skin-to-skin contact with someone who has an active scabies infestation. 

Crusted scabies is even more contagious because crusts of skin may fall off a person’s body. Since the mites can live on that fallen skin tissue for a while, it’s possible to contract crusted scabies from touching clothing or other items that an infected person has recently used. Mites can live for up to three days off the human body.

Additionally, with crusted scabies, you can pass on the mites to someone else, even with brief skin-to-skin contact.

Crusted Scabies Risk Factors

You’re more likely to develop crusted scabies if you have a weakened immune system due to:

• Older age
• Having human immunodeficiency virus (HIV)
• Having cancer, like leukemia or lymphoma
• Having had an organ transplant
• Taking immunosuppressive medications 
  

Scabies is also common in people who are hospitalized or residents of long-term medical facilities, like nursing homes.

Treatment

Medical treatment is necessary to get rid of scabies and crusted scabies. Treatment can be difficult because thick crusts make it tougher for the skin to absorb topical medications. This is why healthcare providers usually treat crusted scabies with a combination of topical and oral medications. 

Doctors will often prescribe oral ivermectin, an antiparasitic and topical medication, for people with severe scabies. In some people, multiple doses of the medication may be necessary to kill the mites and cure scabies.

Topical medications for crusted scabies may include:

• Permethrin cream 5%
• Benzyl benzoate 25%
• Keratolytic cream, to help with crusting
  

Your healthcare provider may prescribe other medications, like antibiotics or antihistamines, to treat itching and prevent infection. 

With treatment, people will see a reduction in symptoms in about four weeks. Some people, especially those with crusted scabies, will require repeat treatments to kill off the mites completely.

Prevention

In addition to treatment, you can also do a few things to prevent passing on the mites to someone else or contracting scabies again. 

The American Academy of Dermatology (AAD) recommends:

• Washing clothing
• Washing towels
• Washing bedding 
• Vacuuming your entire living space 
• Using hot water to clean items 
• Storing items that can’t go in the washing machine in a sealed plastic bag for at least a week
  

Summary 

Crusted scabies, or Norwegian scabies, is a severe form of scabies that often affects people with weakened immune systems. Because the body has a harder time fighting off the infestation, the mites reproduce easily and cause a heavily crusted rash and intense itching.

Crusted scabies is harder to treat than regular scabies because there are so many mites. The thickened and crusted skin may not absorb medication well. Many people with crusted scabies will need multiple rounds of treatment to eliminate the mites.

It's important for people who have come into contact with someone who has crusted scabies to receive treatment since this form of scabies is very contagious.

A Word From Verywell

Crusted scabies can be very uncomfortable, but the mites aren’t typically dangerous. The biggest issue is the potential for infection due to scratching. 

Get in touch with a healthcare provider as soon as you notice potential signs of scabies. Untreated, the condition will get worse, and only medical treatments can get rid of scabies mites. 

The people around you might benefit from treatment, too. Your healthcare provider will likely ask you about your sexual partners or people you live with who might have been exposed.