Heat rash on arms: what to know

Heat rash, also called miliaria or prickly heat, occurs when sweat is held near the surface of the skin. Small raised spots, a rough texture, stinging, or itch can appear on exposed or covered parts of an arm. On deeper skin tones, redness may be subtle or absent; the area may look darker, greyish, purple, or simply feel rough and irritated. A rash that spreads, becomes tender, leaks fluid, or does not settle may have another cause, such as contact irritation or infection.

Move into a cooler place, loosen sleeves, and let sweat dry rather than rubbing the skin. Rinse gently with cool or lukewarm water, pat dry, and choose loose, breathable clothing. Avoid thick oils, fragranced products, scrubbing, and heat until the skin calms. A bland moisturiser may support the barrier once the area is dry; see Emollient Therapy for more on this approach. A pharmacist or clinician may advise a short course of Topical Corticosteroids when inflammation is significant, but these medicines are not suitable for every rash or every body site.

Arrange medical advice if the rash is painful, hot, rapidly worsening, blistered, crusted, or producing pus, or if you feel unwell with fever. Seek urgent help for facial swelling, breathing difficulty, faintness, or a rapidly spreading rash. If cooling and gentle care do not improve the problem, an examination can distinguish heat rash from other causes of Skin Bumps, Skin Rash, or Skin Redness.

Ask whether the pattern fits heat rash, whether a medicine or product could be irritating your arms, and which treatment is appropriate for your skin. Mention recent heat exposure, sweating, new clothing or cosmetics, itch versus pain, and any change in colour or texture.