Salicylic Acid for a Healthier Scalp: What You Need to Know
You may have seen salicylic acid listed as an ingredient in shampoos and other hair care and skin products (such as products for acne). But what exactly does it do, and can it help your scalp?
What Is Salicylic Acid?
Salicylic acid is a natural compound found in willow tree bark. It works as a gentle exfoliant, helping to remove dead skin cells while keeping the skin hydrated. It also breaks down waxy sebum (oil) that can build up on the scalp, leading to flakiness, dryness, and itchiness.
How Does Salicylic Acid Help the Scalp?
Because of its exfoliating properties,[i] [ii] [iii] [iv] [v] salicylic acid is effective in helping clear the dead skin build up than can occur in some scalp conditions. It does not treat any underlying problems, but does help remove any excess dead cells that you can find with conditions such as:
- Dandruff – Caused by an overgrowth of the fungus Malassezia, leading to flaking and itching. Factors like stress, genetics, weakened immunity, and harsh hair products can make dandruff worse. Read more about dandruff here.
- Seborrhoeic Dermatitis – A more severe form of dandruff that also causes thickened, flaky, and itchy skin.
- Tinea Capitis (Scalp Ringworm)[vi] – An infectious fungal infection, commonest in children under 10, that causes hair loss, redness, and scaly patches.
- Psoriasis – A chronic inflammatory condition that causes red, scaly plaques on the scalp.
Because of these exfoliation properties the benefits of Salicylic Acid for the scalp include:
✔ Exfoliate dead skin cells
✔ Soften the outer skin layer
✔ Lock in moisture
✔ Hydrate the scalp
✔ Reduce dryness
✔ Control oil production
✔ Minimize dandruff flakes
✔ Break down sebum buildup
✔ Relieve itchiness
It does not however treat the underlying conditions.
Side effects of salicylic acid
Adverse side effects from salicylic acid are rare, but they can include:
- Burning
- Redness
- Peeling of skin
- Allergic reaction (rash, itchiness, irritation, swelling)
- Drying of the skin and hair
Salicylic acid is in the same drug class as aspirin (salicylate). Therefore, you should not use this product in young children as it can cause salicylate poisoning.
It is also recommended to consult a doctor if you have kidney or liver disease before using salicylic acid to avoid complications.
Salicylic Acid and Hair Growth: Does It Help?
Some shampoos claim that salicylic aids hair growth. However there is limited scientific evidence to prove this.
There is a small study[viii] suggesting salicylic acid might help with alopecia, but the research is not strong, and the treatment used included other ingredients- so it’s not clear exactly how the salicylic acid helped if at all.
However – there is research that dandruff and seborrhoeic dermatitis can cause hair loss, also excessive itching the scalp can cause damage to hair follicles which in turn may lead to hair loss[ix].
So, in theory treating an itchy, inflamed scalp can indirectly prevent hair loss, however the evidence really isn't there that shows salicylic acid can treat hair loss and certainly seems to have no place in male or female pattern hair loss.
Final Thoughts
Salicylic acid is a useful ingredient for scalp health, particularly for managing scalp problems that involve a build-up of excess dead skin and oily skin such as dandruff, seborrhoeic dermatitis, tinea capitis and psoriasis. With some people it can have some side effects though, so do use with caution. It is not needed routinely on a healthy scalp and should not be used with children unless under medical supervision.
It has not be proven as a hair growth treatment.
[i] https://pmc.ncbi.nlm.nih.gov/articles/PMC3579488/
[ii] https://onlinelibrary.wiley.com/doi/full/10.1111/jocd.1674
[iii] https://pmc.ncbi.nlm.nih.gov/articles/PMC11705510/
[iv] https://www.sciencedirect.com/science/article/pii/S0022202X15526572
[v] https://dermnetnz.org/topics/salicylic-acid