Heat Rash: What Is It, Symptoms & Treatment

Medical review: Drª. Aleksana Viana
Dermatologist
October 2022

A heat rash occurs when the body temperature becomes elevated, leading to the appearance of small blisters or red rashes on the skin. These can be itchy and cause swelling in the affected areas. 

Although the exact cause of a heat rash is not well known, it may be related to an allergic reaction to sweat, or to a response from the nervous system caused by stress and anxiety. It can occur on vey hot or humid days or after an intense workout, for example. 

A heat rash usually do not require medications, and can be relieve with home remedies like taking a cold bath or applying soothing creams. Nonetheless, it is important to see a dermatologist if you experience frequent or severe sweat blisters. 

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Main symptoms

The main symptoms of a heat rash include: 

  • Small red blisters that appear in areas exposed to the sun or in areas prone to sweating 
  • Itchiness in the affected areas
  • Crusting of the blisters from itching 
  • The emergence of a red rash on the skin
  • Swelling in the affected areas

A heat rash can occur at any age, although it is most often observed in babies, older adults, and bedridden patients. Sweat blisters are typically seen in the neck and armpits. 

In addition to these symptoms, patients who stay in the sun or hot environments for prolonged periods of time may also experience nausea, diarrhea, difficulty breathing, vomiting and fatigue. These are usually symptoms of overheating and should be assessed by a doctor. 

Treatment options

Treatment of sweat blisters involves hydrating the skin well with soothing lotions that contain aloe vera or calamine. You should also bathe in cold water, drink plenty of water, use light clothing, and avoid excessive sweating. Affected areas or the skin should be kept uncovered. 

These measures may not be sufficient in managing severe cases of heat rashes, and therefore, should be assessed by a doctor. The doctor may opt to prescribe lotions, creams or ointments with corticosteroids, like hydrocortisone or betamethasone. Topical medications with corticosteroids should be used in small quantities and applied in a thin layer for a specified amount of time to prevent further skin damage. 

For babies, you should pat affected areas, like the neck, with a dry, clean cloth. You can also apply baby powder to prevent friction and irritation. Babies with very irritated skin can be bathed in water several times throughout the day, being sure to avoid any shampoos or soaps. 

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Edited by Tua Saude editing team in October 2022. Medical review completed by Drª. Aleksana Viana - Dermatologist in October 2022.

References

  • FUKUNAGA, Atsushi et al. Cholinergic urticaria: epidemiology, physiopathology, new categorization, and management. Clin Auton Res. Vol 28. 103-113, 2018
  • SOCIEDADE BRASILEIRA DE DERMATOLOGIA. Urticária. Available on: <https://www.sbd.org.br/dermatologia/pele/doencas-e-problemas/urticaria/73/>. Access in 20 Sep 2022
Show more references
  • ASSOCIAÇÃO BRASILIERA DE ALERGIA E IMUNOLOGIA. Alergia ao suor? É a urticária colinérgica. Available on: <https://asbai.org.br/alergia-ao-suor-e-a-urticaria-colinergica/>. Access in 20 Sep 2022
Medical review:
Drª. Aleksana Viana
Dermatologist
Post graduate in Clinical Dermatology, Cosmiatric and Surgery by CMMG in 2012 and member no. 16907 of CRM-PE, Brazil.