Korean Skincare for Oily Skin: Diet, Zinc and Daily Habits

I'm Dr. Hongseok Kim, a board-certified dermatologist with 21 years of practice and the medical director of VOS Dermatology Clinic in Gangnam, Seoul, right in front of Dosan Park. At VOS I see every patient myself, from the first consultation to the last treatment.

Korean skincare for oily skin usually means a cleanser, a toner and something with niacinamide. Those help, but many patients tell me they do all of that and still feel greasy by noon. In this video I filmed outdoors on a 34°C June day to talk about what drives sebum besides cosmetics. This page is based on my YouTube video from June 2024; I rewrote it for readers abroad. The video above can be watched with translated captions.

Why does oily skin get worse in summer?

Short answer: heat and humidity both raise sebum, and sweat makes it spread and flow more easily.

The figures I quote in the video are these: in summer, each 1°C rise in temperature increases sebum by about 10%, and the effect is especially noticeable above 30°C (in the video at 01:20). When humidity rises from 30% to 60%, sebum goes up by another 20 to 30%. On the day we filmed, it was about 35°C with around 50% humidity, which is roughly double the normal level.

Heat also makes you sweat, and sweat mixed with sebum makes the surface look greasier. That mixture is more fluid, so sebum comes out more easily. On top of that, warm skin has more blood flow and the pores widen, so every exit route for sebum opens up. At the peak of summer, avoiding very hot and humid places is the simplest way to keep oil down.

Can what I eat make my skin oilier?

Short answer: yes; a diet high in sugar and fat can raise sebum through insulin resistance and the stress hormone cortisol.

I have always stressed cleansing and the right cosmetics, but this time I wanted to talk about diet (in the video at 02:48). Food high in sugar and fat raises blood sugar quickly, and the body releases insulin to bring it down. When insulin is released again and again, cells respond to it less. That is insulin resistance: plenty of nutrients outside the cell, but not enough getting in.

Cells under that strain signal that something is wrong, and the brain triggers the adrenal glands to release cortisol. Cortisol stimulates the oil glands, so sebum rises. This is why some people use niacinamide, AHA and BHA faithfully and still struggle: the focus is too narrow. If your diet is high in sugar and fat, changing that is part of oily skin care.

Does zinc help with oily skin?

Short answer: zinc can help regulate sebum, mainly by reducing the hormone DHT, and it also has antioxidant and anti-inflammatory roles.

Zinc inhibits 5-alpha-reductase, the enzyme that converts testosterone into DHT (in the video at 05:05). DHT increases sebum, which is one reason acne is common in puberty when this hormone rises. That is also why zinc is often suggested for people with hair loss, acne or high sebum.

Zinc is also an antioxidant, it is needed to build the phospholipids in cell membranes, and it helps the body make metallothionein, a protein that protects skin from damage linked to heavy metals. It helps calm inflammation too, which matters when oiliness comes with acne.

How much zinc, and what to watch out for

Short answer: the range I mention is 15 to 30 mg a day for sebum, no more than 40 mg a day, ideally after checking with a pharmacist or doctor.

Zinc is itself a metal, so too much can cause toxic reactions (in the video at 06:51). Minerals also interact: high zinc intake can lower copper, and high copper can lower zinc. Take an appropriate amount and keep track of what you take.

Zinc can cause real stomach discomfort; it does for me. Taking it with a meal is one way around that, and absorption is said to improve when it is taken with vitamin C and magnesium. If your stomach struggles, taking it with food is better than not taking it at all.

Is there a clinic treatment for excess sebum?

Short answer: skin botulinum toxin, given as very fine, shallow injections, acts on the oil glands to reduce sebum and can make pores look tighter.

I have talked about this treatment often (in the video at 08:29). It works directly on the sebaceous glands, reduces sebum, calms inflammation and can tighten the look of pores, so it addresses several of the summer problems at once. At VOS it is part of our botulinum toxin treatments, and my article on micro-dose toxin injections for oil and pores explains how it is planned. For a non-injectable option, our HydraFacial treatment uses vacuum cleansing to clear sebum and impurities from pores. If pores are your main concern, what actually shrinks pores covers the other options.

Five home-care habits for oily skin

Short answer: don't over-cleanse, moisturise, use antioxidants and gentle exfoliation, wear sunscreen, and use oil-absorbing ingredients.

These are the skincare habits I recommend for oily skin, rather than any particular product (in the video at 08:56).

1. Don't over-cleanse. Washing until skin feels tight dries it out and, ironically, stimulates more sebum. Choose a cleanser and routine that leave skin comfortable.
2. Moisturise well. Well-hydrated skin tends to produce less sebum.
3. Use antioxidants. Inflammation can damage the skin barrier and set off other problems, so an antioxidant step helps.
4. Exfoliate with AHA or BHA in moderation. They smooth the surface and help calm inflammation, which can help with acne and oil. My video note on choosing between AHA and BHA explains which suits which skin.
5. Wear sunscreen. UV light can oxidise sebum and trigger inflammation.

Ingredients such as niacinamide, or clay that absorbs oil, can also help. If oil comes with breakouts, my guide on when Korean face care for acne is not enough explains when to see a dermatologist. You can also read creator experiences at VOS.

Skincare matters, but reducing sugar and fat in your diet and considering zinc can help sebum control from the inside (in the video at 10:07). Results, timing and recovery vary from person to person, and the right plan for you is decided at an in-person consultation.

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Results, swelling and recovery vary from person to person. This page is general information from VOS Dermatology Clinic based on Dr. Kim's video and does not replace an in-person consultation.