How Long Do Heat Rashes Last?

Symptoms of heat rashes include:

• Small, raised spots on the skin
• May look like a cluster of tiny bubbles under the skin or like a cluster of small pimples
• An itchy, prickly feeling
• Mild swelling
• Skin irritation
• Skin redness (less obvious on brown or black skin)
• Rash often appears on the head, neck, chest, or anywhere where the skin rubs together (such as an armpit)

See a doctor if you have a heat rash and symptoms of other heat-related illness including heat exhaustion or heat stroke (a medical emergency) such as: 

• Pale, cool, moist skin
• Profuse sweating
• Core temperature elevated to usually more than 100° F (37.7° C) but not above 104° F (40° C) (heat exhaustion)
• Body temperature of 104°F (40°C) or higher (heat stroke)
• Dizziness or lightheadedness
• Brain symptoms 
  • Confusion or problems thinking clearly
  • Seeing or hearing things that aren't real (hallucinations)
  • Trouble walking
  • Seizures
  • Fainting
  • Coma
• Fast breathing (hyperventilation)
• Fast heartbeat
• Skin redness (flushing) and warmth or heat
• Dry skin
• Vomiting or diarrhea
• Muscle cramps or weakness
• Headaches
• Absence of sweating due to dehydration
• Changes in blood pressure (may be high or low)

Causes of heat rashes include:

• Clogged sweat ducts that cause perspiration to become trapped under the skin
• Underdeveloped sweat ducts
• Hot, humid weather or tropical climates
• Intense physical activity that causes excessive sweating
• Overheating

Babies and young children are more prone to heat rash because they are unable to regulate body temperature as well as adults. 

Initial treatment for heat rashes and mild heat-related illness usually includes:

• Getting out of a hot, humid environment into a cool, dry environment 
• Cooling measures such as cool baths or clean cloth dipped in cold water and applied to areas with rash or sunburn
• Fluid intake
• Rest/stopping physical activity
• For skin itching: 
  • Calamine lotion
  • Antihistamines
  • Hydrocortisone cream