Việt Nam
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You’re using serums, exfoliating regularly, masking consistently — yet your skin is still dull, your pores are enlarged, or it’s becoming increasingly sensitive. The problem usually isn’t a lack of products. It’s that you’re doing the wrong things correctly. Here are the 5 most common skincare mistakes our dermatologists at HT Derma Aesthetic see in the clinic — and how to fix each one.
Mistake 1: Skipping Sunscreen — or Using It Wrong
This is the most common skincare mistake — and the one with the most damaging consequences. No vitamin C serum, retinol, or laser treatment works effectively without proper sun protection. UV radiation destroys collagen and activates pigmentation faster than any product can repair.
Common sunscreen mistakes:
Using too little: The correct amount for the face is about ¼ teaspoon (~1.5ml). Most people apply roughly one-third of this — meaning the actual SPF protection is far lower than the number on the label.
Not reapplying: SPF loses effectiveness after 2–3 hours. If you’re going outdoors, reapplication is essential — one morning application does not last all day.
Assuming indoors means safe: UVA rays penetrate glass. Sitting near a window all day without sunscreen still exposes your skin to cumulative UV damage.
Using SPF powder as a substitute: The SPF in setting powder is insufficient for real protection — it’s a top-up layer, not a replacement for sunscreen.
Fix: SPF 50+, PA++++ every morning — regardless of weather, indoors or outdoors. Reapply every 2–3 hours when spending time outside.
Mistake 2: Over-Exfoliating Your Skin
Done correctly, exfoliation brightens skin and improves absorption of other products. But overdoing it has the opposite effect — it strips the young keratinocyte layer, thins the skin barrier, and turns normal skin into sensitive skin.
Signs you’re over-exfoliating:
Unusual redness and shine, especially after cleansing. Stinging sensation when applying any product. More small breakouts appearing despite regular exfoliation. Increased sun sensitivity compared to before.
Correct frequency: AHA/BHA — 2–3 times per week for normal skin, once per week for sensitive skin. Physical exfoliation no more than once per week. Never combine both on the same day.
If your skin is currently reactive or irritated — stop all exfoliation completely for 2–4 weeks and focus on barrier repair first.
Mistake 3: Using Too Many Products at Once
Many people build routines on the assumption that more is better — 3–4 serums, multiple toners, essences, ampoules. Not only is this wasteful, it’s counterproductive.
Ingredient conflicts: Using retinol and AHA/BHA in the same evening session causes cumulative irritation. High-concentration vitamin C and niacinamide used simultaneously can create unwanted reactions.
Skin has an absorption limit: Skin can only absorb a finite amount of active ingredients each day. Layering 5 serums does not deliver 5 times the benefit.
Harder to identify problems: If your skin reacts badly, you won’t be able to identify which product is responsible.
Fix: Maximum 1–2 active serums in your routine. Morning: Vitamin C + sunscreen. Evening: Retinol or AHA/BHA — never both on the same night.
Mistake 4: Skipping Moisturizer Because of Oily Skin
This is one of the most common skincare mistakes among people with oily skin — especially in Vietnam’s hot and humid climate. Oily skin and hydrated skin are two different things. Excess oil production is often a compensatory response when skin is lacking water — sebaceous glands overwork to compensate for missing moisture. Skipping moisturizer makes skin more dehydrated — which triggers even more oil production.
Fix: For oily skin, choose a gel or lightweight lotion moisturizer — oil-free, containing Hyaluronic Acid and Niacinamide. Apply a thin layer immediately after cleansing while skin is still slightly damp.
Mistake 5: Impatience — Switching Products Too Frequently
Most skincare actives need at least 4–12 weeks to show clear results. Retinol takes 3 months. Niacinamide takes 4–8 weeks. Vitamin C takes 6–8 weeks. Yet many people give up after 2–3 weeks because they “don’t see anything” and move on to something new — then restart the cycle from scratch.
Switch immediately if: Skin turns red, stings, itches, or develops a rash within the first 48–72 hours of a new product. Breakouts flare severely and don’t subside after 4 weeks. Stinging or burning sensation lasts longer than 10–15 minutes after application.
Fix: Give each new product a minimum of 4–6 weeks before evaluating. Photograph your skin under the same lighting conditions every 2 weeks to track progress objectively.
Frequently Asked Questions About Common Skincare Mistakes
Why does my skin get worse after starting retinol?
This is retinol purging — a normal skin clearing response as retinol accelerates cell turnover, bringing hidden congestion to the surface. It typically lasts 4–6 weeks and self-resolves. This is different from true irritation (significant redness, burning, excessive flaking) — in that case, reduce frequency or discontinue use.
Can vitamin C and retinol be used together?
Not at the same time. Use vitamin C in the morning (antioxidant protection) and retinol in the evening (cell renewal). Both active ingredients perform best when used separately.
Can I use a sheet mask when my skin is irritated?
It depends on the mask. A simple hydrating sheet mask can help calm irritated skin. However, clay masks, exfoliating masks, and masks with strong actives should be avoided completely when skin is in an irritated state.
“Effective skincare isn’t about quantity — it’s about understanding your skin correctly.”
If you’ve tried multiple approaches and your skin still isn’t improving, a skin consultation and analysis at HT Derma Aesthetic will help identify exactly what’s happening and recommend the most suitable routine for your skin type.