Most scalp-care formulas for oily scalps lean on harsh sulfates or salicylic acid to strip sebum away. The result is a clean feeling for about six hours, then the scalp rebounds — and the cycle repeats. Aged black garlic offers a different approach.
A 30-day transformation
Fresh garlic is fermented for 30 to 45 days under controlled humidity (60–80%) and temperature (60–80°C). During fermentation, the volatile sulfur compound allicin — responsible for the sharp smell and bite of fresh garlic — converts into S-allyl cysteine (SAC), a stable, water-soluble antioxidant.
SAC is what makes aged black garlic interesting cosmetically: it has none of the volatile sulfur smell, and it stays stable in formulation for 24+ months at room temperature. That stability is what most botanical extracts cannot offer.
What it actually does on the scalp
Three documented effects, in order of clinical strength:
- Calms 5-alpha reductase activity locally. The enzyme that converts testosterone to DHT (the hormone implicated in oily scalp and sebum overproduction) is modulated by SAC at topical concentrations. This is not the same as oral 5-alpha-reductase inhibitors — it is a gentle, local effect.
- Antimicrobial against malassezia. The fungal species most associated with sebum-related dandruff is sensitive to SAC.
- Antioxidant. Free radicals from heat tools, hard water, and pollution degrade scalp lipids and trigger compensatory sebum production. SAC neutralizes them.
Why the ritual carries it in two forms
Our No. 03 Black Garlic series carries the ingredient in two forms. The shampoo uses the water-friendly extract, which does its balancing work at the scalp during the wash. The conditioner, mask and leave-in carry garlic oil instead — a lipid form that stays with the hair longer and conditions the lengths, so a clarifying routine does not leave hair squeaky or stripped.
Together, the extract works on balance at the source while the oil keeps lengths supple — and the scalp feels lighter for longer between washes instead of rebounding within hours.
How to use it
Two to three times a week, alternating with No. 01 Hyaluronic Acid on dry days for balance. Apply to the scalp first, work down through lengths, leave 1–2 minutes, rinse. For severe oily-scalp cases, the No. 03 Hair Mask once a week extends the rebalancing effect.
Most users report a noticeable shift within 2–3 weeks: longer time between washes, a calmer scalp, less mid-day flatness at the roots. Patience matters — fermented ingredients work gradually, not overnight.
Aged black garlic is one of the rare ingredients where traditional fermentation and modern cosmetic chemistry meet at the same answer. We think it is the most underused scalp ingredient in the category.