Many people notice tiny white spots appearing on their arms or legs during the summer months. While these spots can be alarming, they’re often harmless and become more noticeable after sun exposure. The surrounding skin tans, making the lighter spots stand out.

However, not all white spots have the same cause. Here’s what dermatologists say about the most common reasons, how to tell them apart, and the best ways to treat them.

Why Do White Spots Become More Noticeable in Summer?

When your skin is exposed to sunlight, healthy skin produces more melanin (the pigment that gives skin its color). Areas that have lost pigment—or produce less pigment—don’t tan as easily, making white spots much more visible.

This is why many people only notice these spots during the warmer months.

The Most Common Causes of White Spots

1. Idiopathic Guttate Hypomelanosis (IGH)

One of the most common causes of tiny white spots on the legs and arms, especially in adults over 40.

Signs:

• Small, round white spots (2–5 mm)
• Usually on the shins, forearms, and shoulders
• Smooth skin
• No itching or pain
• More noticeable after tanning

Causes:

Experts believe it’s linked to:

• Years of sun exposure
• Natural aging
• Genetics

Treatment:

There is no cure, but appearance can be improved with:

• Daily sunscreen
• Prescription retinoid creams
• Certain laser treatments
• Microneedling (performed by a dermatologist)

2. Tinea Versicolor (Fungal Infection)

A harmless yeast that naturally lives on the skin can sometimes overgrow in warm, humid weather.

Signs:

• White, pink, or brown patches
• Fine scaling
• Mild itching
• Usually affects the chest, back, neck, and upper arms

Treatment:

• Ketoconazole shampoo
• Selenium sulfide lotion or shampoo
• Antifungal creams
• Oral antifungal medication for severe cases (prescribed by a doctor)

Even after the fungus is gone, normal skin color may take weeks or months to return.

3. Vitiligo

Vitiligo is an autoimmune condition where pigment-producing cells are destroyed.

Signs:

• Bright white patches
• Well-defined borders
• Often symmetrical
• Can affect hair, lips, hands, elbows, knees, and face

Treatment:

A dermatologist may recommend:

• Topical corticosteroids
• Calcineurin inhibitors
• Phototherapy (light treatment)
• Newer prescription medications for some patients

Early treatment often leads to better results.

4. Post-Inflammatory Hypopigmentation

After eczema, insect bites, burns, cuts, or rashes heal, the skin may temporarily lose pigment.

Signs:

• White patches where the injury occurred
• Usually fade gradually over several months

Treatment:

• Moisturizers
• Sunscreen
• Treating the underlying skin condition

5. Dry Skin (Xerosis)

Very dry skin can create pale, flaky patches that look lighter than surrounding skin.

Treatment:

• Thick moisturizing creams
• Gentle cleansers
• Avoid overly hot showers

How Dermatologists Diagnose White Spots

Diagnosis may include:

• A physical skin examination
• Reviewing your medical history
• Examining the skin with a Wood’s lamp (special ultraviolet light)
• Skin scraping if a fungal infection is suspected
• Occasionally, a skin biopsy if the diagnosis is uncertain

How to Treat White Spots

Treatment depends on the underlying cause.

Step 1: Protect Your Skin

Use a broad-spectrum sunscreen (SPF 30 or higher) every day. This helps prevent surrounding skin from tanning, making white spots less noticeable.

Step 2: Moisturize Daily

Keeping the skin hydrated improves overall skin health and can reduce the appearance of dry, pale patches.

Step 3: Follow the Right Treatment

• Antifungal products for fungal infections
• Prescription creams for pigment disorders
• Dermatologic procedures such as laser therapy or phototherapy when appropriate

Avoid using home remedies such as lemon juice, toothpaste, bleach, or harsh scrubs, which can irritate the skin and make discoloration worse.

When Should You See a Dermatologist?

Make an appointment if:

• White spots are spreading quickly.
• The patches become very noticeable or sharply defined.
• They itch, hurt, or become inflamed.
• You have a personal or family history of autoimmune disease.
• Over-the-counter treatments don’t help after several weeks.
• You’re unsure of the cause.

A dermatologist can identify the cause and recommend the most appropriate treatment.

Can White Spots Be Prevented?

While not all white spots can be prevented, these habits may reduce your risk:

• Wear sunscreen every day.
• Avoid excessive sun exposure.
• Keep your skin well moisturized.
• Shower after heavy sweating.
• Wear breathable clothing in hot weather.
• Treat fungal infections promptly.

The Bottom Line

White spots that appear during summer are often harmless and become more noticeable because the surrounding skin tans. Common causes include sun-related pigment loss (idiopathic guttate hypomelanosis), fungal infections, vitiligo, or temporary pigment changes after skin irritation.

The best treatment depends on the cause, so it’s important not to assume all white spots are the same. If the spots are spreading, changing, or causing concern, a dermatologist can provide an accurate diagnosis and recommend the most effective treatment.

Note: The image alone cannot determine the exact cause of white spots. Similar-looking spots can result from different skin conditions, so an in-person evaluation is often needed for a definitive diagnosis.