Why do I get white spots on my skin in the summer and how can I treat them? A dermatologist answers.

If you’ve noticed these spots, you’re not alone. They’re surprisingly common, especially as we age. But what are they? Are they harmless? And is there anything you can do about them?

Let’s explore the most likely causes—and when you might want to mention them to a doctor.

The Most Common Cause: Idiopathic Guttate Hypomelanosis

The medical name is a mouthful, but the condition itself is simple: idiopathic guttate hypomelanosis (often called IGH).

Let’s break it down:

  • Idiopathic – The cause isn’t fully understood

  • Guttate – Latin for “teardrop-shaped”

  • Hypomelanosis – Loss of skin pigment

What it looks like:

  • Small, flat white spots, usually 1-5mm in size

  • Most commonly on sun-exposed areas: shins, forearms, shoulders

  • Smooth texture (not scaly or raised)

  • More common as we age (often starting after 40)