There are many possible reasons that your scalp smells, including:
1. Not Washing Your Hair Enough
“If you don’t wash regularly, you may experience a buildup of oil, sebum, and sweat that can leave an odor,” Julie K. Karen, MD, a dermatologist at Complete Skin MD in New York City.
This is especially true if you use a lot of hair products, exercise a lot, are prone to excessive sweating, or are going through hormonal changes (such as during puberty or menopause).
2. Over-Washing
Another common mistake is washing your hair too often. Mehmet Göker, MD, a dermatology specialist at Vera Clinic in Istanbul, says over-washing your hair can “damage your scalp’s microbiome,” which “provides easier access to bad bacteria and fungi, which can cause inflammation and itching.”
Kemunto Mokaya, MD, a board-certified dermatologist in Houston, says it’s important to wash your scalp with products that are suited to your texture and skin type.
In general, people with straight hair textures can often wash their hair daily or every other day, while people with curly hair textures may benefit from shampooing every five to seven days. If you have specific concerns or belong to a group with particular hair care needs, consult with a dermatologist for personalized advice.
3. Your Diet
Dr. Mokaya says your diet might be the culprit, especially “if you eat excessively pungent foods like garlic and onion, or if you have a heavy animal-based diet.”
Research shows that garlic, specifically, can negatively affect your body odor in general. The same can also be said for red meat, according to Cleveland Clinic.
4. Air Pollution
A smelly scalp may also be caused by environmental factors like air pollution. If you live in an area where the air is highly polluted, particles may cling to your hair and scalp.
Research shows that pollution creates volatile organic compounds (VOCs). Many VOCs can have a smell to them, according to the Minnesota Department of Health.
5. Seborrheic Dermatitis
Seborrheic dermatitis is a common skin condition thought to be caused by an overgrowth of yeast that lives on the scalp.
It’s marked by itchy, red patches, greasy yellow scales, or powdery flakes on your scalp (dandruff), according to Mayo Clinic. Seborrheic dermatitis can cause your scalp to smell.
6. Scalp Psoriasis
Scalp psoriasis can cause reddish patches, silvery-white scales, and dandruff-like flaking on your head, according to the American Academy of Dermatology.
Your scalp may also burn or itch, and you might have temporary hair loss. If it’s not taken care of properly, psoriasis can cause your scalp to smell.
7. Infection
Skin infections — usually fungal infections on the scalp — can lead to unpleasant odors.
One possibility is tinea capitis, or ringworm of the scalp, according to Mount Sinai. Ringworm is usually itchy and marked by round areas of scaly skin that are red and swollen, pus-filled sores, and bald patches.
Infection is more likely to occur if you don’t wash your hair often and have wet skin for a long time (such as from sweating).