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Skin signs of coma

Authors: Claire Jordan Wiggins, Riyad N.H. Seervai, Medical Students, Baylor College of Medicine, Houston, Texas, USA. DermNet NZ Editor in Chief: Adjunct A/Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand. Copy edited by Gus Mitchell. June 2020.

What is coma?

Coma describes prolonged unconsciousness when the patient does not move or respond to a painful stimulus, light, or sound. Causes of coma include head injury, stroke, brain tumour, drugs, alcohol, diabetes, and infection.

Examination of the skin of a comatose patient provides information about the cause of coma and the effects of the coma on the body, including skin colour and temperature, coma blisters, and pressure ulcers.

Skin colour

Colour changes in the skin may reveal a potential cause of the coma.

  • White or ashy colouring may indicate blood loss or other forms of anaemia.
  • Yellow may indicate jaundice from liver damage.
  • Red skin may indicate an immune-related reaction.
  • Purple or green skin could indicate bruising.

Colourful skin changes and associated swelling provide important clues for cellulitis, venous stasis, or deep vein thrombosis, for example [1].

Skin temperature

Fluctuations in skin temperature may reflect the depth of a coma.

  • Comatose patients with a higher level of consciousness have temperature fluctuations in circadian rhythm, similar to a healthy individual.
  • Patients in a deeper coma have a more constant temperature.
  • Unusually high or low temperature may indicate infection or the loss of the patient’s ability to control body temperature due to brain injury [2].

Coma blisters

Traditionally associated with barbiturate overdose, coma blisters present as dusky bullae. They are thought to be caused by hypotension-associated necrosis. Coma blisters appear within 48–72 hours of the onset of coma and typically self-resolve after several weeks. Sweat gland necrosis may be noted on histopathology [3].

Pressure ulcers

Bedbound hospitalised patients are at risk for pressure ulcers, especially patients who cannot communicate or who lose sensation. Prevention of pressure ulcer includes limiting pressure, friction, and shear, while managing comorbid conditions that may interfere with wound healing, such as diabetes [4].

Pressure ulcer

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Related information



  1. Bateman DE. Neurological assessment of coma. J Neurol Neurosurg Psychiatry 2001; 71: i13–7. DOI: 10.1136/jnnp.71.suppl_1.i13. PubMed
  2. Blume C, Lechinger J, Santhi N, del Giudice R, et al. Significance of circadian rhythms in severely brain-injured patients: A clue to consciousness? Neurology 2017; 88: 1933–41. DOI: 10.1212/WNL.0000000000003942. PubMed
  3. Rocha J, Pereira T, Ventura F, Pardal F, Brito C. Coma Blisters. Case Rep Dermatol. 2009; 1: 66–70. DOI: 10.1159/000249150. PubMed
  4. Bhattacharya S, Mishra RK. Pressure ulcers: Current understanding and newer modalities of treatment. Indian J Plast Surg 2015; 48: 4–16. DOI: 10.4103/0970-0358.155260. PubMed

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