What Makes Skin Oily
Oily skin is characterised by overactive sebaceous glands — typically driven by androgenic hormones (testosterone, DHT) that stimulate sebum overproduction. The result: a shiny appearance, enlarged pores, and a predisposition to comedone formation and acne.
Sebum itself is not the enemy. It's a complex mixture of triglycerides, wax esters, squalene, and fatty acids that forms part of the acid mantle and helps seal moisture in. The problem is excess sebum, particularly when the composition shifts toward pro-inflammatory lipid oxidation products.
Why Stripping Oil Backfires
When you aggressively remove sebum — with alcohol toners, harsh cleansers, or over-exfoliation — the skin's sebaceous glands upregulate production in a compensatory response. This is called reactive seborrhoea: stripping → perceived lipid deficit → increased sebum production → more oiliness.
The paradox of oily skin care: Moisturising oily skin does not make it oilier. Using a lightweight, non-comedogenic moisturiser can actually reduce sebum production by signalling to the skin that lipid levels are adequate.
Pore Size: What You Can and Can't Change
Pore size is largely genetic — determined by follicle diameter and sebaceous gland size. It cannot be permanently reduced by skincare. What you can do:
- Clear pore contents: BHA (salicylic acid) dissolves sebum plugs inside follicles, making pores appear smaller
- Strengthen pore walls: Retinoids stimulate collagen around follicles, improving structural support
- Reduce sebum volume: Niacinamide inhibits sebum transfer from sebocytes; zinc regulates androgen-driven overproduction
Best Ingredients for Oily Skin
| Ingredient | Function | Concentration |
|---|---|---|
| Salicylic Acid (BHA) | Oil-soluble; dissolves sebum inside pores | 0.5–2% |
| Niacinamide | Reduces sebum secretion, shrinks pore appearance | 5–10% |
| Zinc (PCA Zinc) | Inhibits 5α-reductase (androgen conversion) | 1–2% |
| Retinol / Adapalene | Regulates cell turnover, prevents comedone formation | 0.025–0.3% |
| Clay (kaolin, bentonite) | Absorbs excess surface sebum | In masks 1–2x/week |
For building a full oily-skin routine, see our Routine Lab. For the acne connection, visit Acne solutions.