Erythema ab igne from hot water bottles

Why does this happen?

Erythema ab igne (EAI), is a skin condition, also referred to as “hot water bottle rash”, “toasted skin syndrome” and “fire stains”. Women have a higher incidence of erythema ab igne than men. Erythema ab igne was commonly seen in the elderly who stood or sat close to open fires or electric heaters for long periods, however, erythema ab igne has also been reported in young individuals.

It happens when there is prolonged exposure to a heat source (infrared radiation) for a period of time such as a hot water bottle (used for chronic lower back pain), space heaters, laptop computers, heating blankets or heat pads directly onto an area of skin. It can also be caused by occupational hazards for silversmiths and jewelers (face exposed to heat stoves), bakers and chefs (arms, face).

Erythema ab igne is a classic finding in chronic pancreatitis and may also be seen in people with hypothyroidism or lymphoedema.

Is it treatable?

Treatment for EAI can be both preventative and restorative. To obtain relief and reduce skin inflammation, the source of chronic heat exposure must be identified and stopped/avoided. If the area is only mildly affected with slight redness, the condition will resolve itself over several months. If the skin has already been damaged by EAI, it’s recommended to visit a burns unit that can provide skin grafts to repair the affected area long-term.

There is a possibility that squamous cell carcinomas may form. If there is a sore that doesn’t heal or a lump growing within the rash, a skin biopsy should be performed to rule out the possibility of skin cancer. If the lesions demonstrate pre-cancerous changes, the use of 5-fluorouracil cream is recommended. Abnormally pigmented skin may last for years. Treatment with topical tretinoin or laser therapy may improve the appearance.

In order to effectively treat EAI caused by hot water bottle injuries, an experienced healthcare professional should assess the level of skin damage and recommend a tailored treatment plan for maximal skin healing. Reacting quickly and educating yourself about EAI is paramount in helping manage your skin health. If you have a specific question or concern about a skin lesion or disease, please consult a dermatologist.

How long do the marks last?

Erythema ab igne is a reticular, pigmented and telangiectatic dermatosis. Typically the lesions are localized in skin areas directly exposed to the heat source. If mildly affected, it should disappear within a few weeks/months. If the skin is hyperpigmented, the marks may stay for some years.

What are the health risks?

Prolonged heat radiation exposure to the skin can lead to the development of reticulated erythema, hyperpigmentation, scaling and telangiectasias in the affected area. Some people complain of itchiness and a burning sensation, most often, unless a change in pigmentation is seen, it can go unnoticed.

In more serious cases of erythema, the skin can be left darkened, although not usually permanently. There is evidence it can lead to cancer, as occasionally, the first sign of splenomegaly, pancreatitis, pancreatic cancer and other cancers is erythema ab igne when patients apply external heat to relieve the underlying pain.

Erythema ab igne is usually a chronic disease. The most significant long-term risk is the malignant transformation of erythema ab igne into cutaneous squamous cell carcinomas or Merkel cell carcinomas.

This condition can look very similar to a vascular condition called livedo reticularis, which can be associated with a serious underlying disease such as lupus.

How to avoid this condition

The best way to prevent EAI from happening is to limit your exposure to direct chronic heat sources such as hot water bottles, heating pads, and central heating.

Tips on how to use a hot water bottle safely:

• As with any hot item, it needs to be used with caution
• It’s recommended to fill the bottle with hot but not boiling when filling a hot water bottle. It should be comfortable but not burning hot
• Never leave them on for more than 15 minutes at a time
• Make sure you always use protective barriers like towels or blankets between your skin and the source of heat, as this will help reduce the risk of burns or other injuries
• Hot water bottles can cause serious injuries if not filled or handled properly, so it’s especially important for those 18 years of age or younger to be supervised when using them

Sources

• Erythema Multiforme – NHS 
• Erythema Ab Igne – NIH