Every summer, our clinic sees a wave of patients treating what they believe is a sudden acne flare with acne products — salicylic acid, benzoyl peroxide, retinoids — and finding no improvement or, in some cases, worsening of their skin. The reason in many cases: what they are treating is miliaria rubra (prickly heat), not acne. The two conditions look similar, occur in similar locations, and are both more common in summer — but they have completely different causes and require opposite management approaches.

The Appearance

Both conditions produce small red papules on the skin. Both can be widespread on the face, chest, shoulders, and back. The distinguishing features in appearance: miliaria papules are more uniform in size, often have a small vesicle (clear fluid-filled blister) at the tip rather than a whitehead, and tend to appear in a more diffuse, uniform distribution. Acne lesions are more variable — a mix of comedones (blackheads, whiteheads), papules, pustules, and sometimes cysts — and follow a more random distribution linked to sebaceous gland density (T-zone, jawline).

The Sensation

This is the most reliable differentiator. Miliaria produces a distinctive stinging, prickling, or burning sensation — particularly when the skin is warm or sweating. The name “prickly heat” reflects this exactly. Acne lesions are sore or tender on pressure but do not produce this ambient prickling quality. If your skin feels like it is prickling or stinging across a widespread area, miliaria is more likely than acne.

The Trigger

Miliaria appears rapidly after significant heat or sweat exposure — hours, not days. Acne develops over days to weeks. Miliaria improves quickly with cooling and reduced sweating; acne does not respond to these measures. If the rash appeared after a particularly hot period or sweaty event and improves significantly with air conditioning — it is miliaria. Treating miliaria with acne products (particularly retinoids and AHAs that further sensitise the skin) worsens the condition; cooling, calamine, and reduced sweat exposure are what is needed.

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— Dr. Nishita Ranka | Consultant Dermatologist | Dr. Nishita’s Clinic for Skin, Hair & Aesthetics, Hyderabad