Differential Diagnosis for Itching with Hot Weather

• Single most likely diagnosis
  • Eczema (Atopic Dermatitis): This condition is characterized by itchy, inflamed skin that can worsen in hot weather due to increased sweating, which can irritate the skin further.
• Other Likely diagnoses
  • Heat Rash (Miliaria): Caused by blocked sweat ducts, heat rash is common in hot weather and can cause itching, redness, and small bumps on the skin.
  • Dry Skin (Xerosis): Hot weather can dry out the skin, leading to itchiness, especially in individuals who spend a lot of time outdoors or have poor skin hydration habits.
  • Insect Bites: Mosquitoes and other insects are more prevalent in warm weather, and their bites can cause intense itching.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Cholinergic Urticaria: A type of hives that can be triggered by heat, leading to itchy wheals. While not usually deadly, severe reactions can occur, especially if there's an associated anaphylactic response.
  • Polycythemia Vera: A rare blood disorder that can cause itching after hot showers or in hot weather due to the release of histamine from basophils. It's crucial to diagnose this condition due to its potential for serious complications like thrombosis.
• Rare diagnoses
  • Aquagenic Pruritus: A rare condition where contact with water, including sweat, induces intense itching without any visible skin lesions. It can be exacerbated by hot weather.
  • Solar Urticaria: A rare condition where exposure to sunlight or UV radiation leads to the development of itchy wheals. While rare, it's an important diagnosis to consider in individuals who experience itching after sun exposure.