Sudden hyperpigmentation on arms only - What would be the best treatment to address this and how can I prevent this? (Photos)

Thank you for your detailed message and for sharing the images. Based on what you've described and shown, this sudden onset of hyperpigmentation limited to the arms, particularly in someone with a previously clear skin history, minimal sun exposure, and consistent SPF use warrants a few potential considerations:

Possible Causes:
Cumulative Photodamage Even minimal incidental sun exposure over the years (through car windows or during brief walks) can eventually result in pigmentation changes, especially as the skin's ability to repair DNA damage lessens with age.

Hormonal Fluctuations or Internal Triggers - Changes related to hormones (e.g., estrogen or progesterone), medications, or even underlying thyroid dysfunction can sometimes manifest with pigmentation irregularities.

Post-Inflammatory Hyperpigmentation (PIH) – Minor unnoticed trauma, friction from clothing, or inflammatory conditions (such as eczema or folliculitis) can result in pigmentation, particularly in fair or sensitive skin.

Pigmented Purpuric Dermatosis or Vascular Causes – Some pinpoint or reddish spots could represent a vascular condition, which can be exacerbated by heat exposure (like radiators or hot showers) or pressure.

Treatment Options:
Topical Agents: Brightening treatments such as azelaic acid, kojic acid, tranexamic acid, or a mild hydroquinone formulation can be used to reduce pigment unevenness.

Gentle Exfoliation: Incorporate polyhydroxy acids (PHAs) or lactic acid to help improve skin texture and cell turnover without irritation.

Laser or Light Therapy: For persistent or widespread pigmentation, broadband light (BBL) or laser treatments may help restore more even skin tone.

Barrier Protection: Continue using SPF50, but also consider physical barriers (UPF clothing) during incidental sun exposure to enhance protection.

Antioxidants: Topical vitamin C serums can neutralize free radicals and help lighten pigment over time.

Prevention Tips:
Reapply sunscreen every 2–3 hours when exposed, even minimally.

Avoid exposure to heat sources (like radiators) that can cause vascular dilation and increase pigmentation.

Monitor any new marks and consider a full skin evaluation to rule out other dermatoses or systemic conditions.

Though this may appear sudden, it’s often the result of multiple, subtle exposures or triggers compounding over time. If the pigmentation evolves or spreads to other areas, it would be advisable to pursue a more thorough clinical assessment, including lab work.

There can be a number of reasons for the hyperpigmentation you are experiencing.. It could be from incidental sun exposure or hormone fluctuations, among other potential causes. Treatment could include laser treatments which can be used alone or in conjunction with lightening creams. Continue to sun protect your skin as you have been.

Fractional laser is an amazing and highly effective treatment in our office. We use the laser treatment to help with acne scars, large pores, fine wrinkles, tissue collagen loss, scars, sebaceous hyperplasia, active acne, and for brightening dark pigmentation. Although there are very strong fractional lasers such as CO2 laser, we use lighter treatments for corrective skincare and maintenance of results. Our Thulium fractional laser, clear and brilliant laser, and Ultra Thulium laser are excellent options in our clinic. We also perform CO2 fractional and erbium depending on skin tone and tolerance for downtime. Patients do have to use a Melarase cream before and after treatment to help further reduce pigmentation after laser. Melarase AM, Melarase PM, and Melapads can seriously improve surface sun damage and UV related pigmentation. Dark spots can improve with these treatments. I recommend fractional laser for incisional scars as well, especially after plastic surgery.
Best,
Dr. Karamanoukian
Realself100 Surgeon