Retinoids Explained: Differences Between Retinol, Retinal, and HPR (+ Studies)

Hello from Repic Clinic in Gangnam!

Among functional skincare ingredients, Vitamin A derivatives (retinoids) are well-studied, with over 70 years of research supporting their benefits.

Retinoids are known to improve a wide range of concerns: wrinkles, pores, fine lines, skin texture, and pigmentation. Choosing the right type for your skin is key.

In this guide, we’ll cover:

• Retinoid basics

• Differences between Retinol, Retinal, and HPR

• Recent clinical comparisons

• How to select the right retinoid for your skin

What is a Retinoid?

Retinoids are derivatives of Vitamin A that help promote skin cell turnover, the natural process by which skin regenerates.

Normal skin renews roughly every 28 days, but aging and environmental factors can slow this cycle. Retinoids help restore this turnover, addressing acne, pigmentation, and rough skin texture.

Common retinoids in skincare include Retinol, Retinal, and HPR, each with unique properties.

Retinol vs Retinal vs HPR: What’s the Difference?

Retinol Molecular Structure

Retinol

• Converts into retinal → then retinoic acid in 2 steps

• Slower results, but stable and gentle

• Most widely used and popular form

Retinal Molecular Structure

Retinal

• Converts into retinoic acid in 1 step

• Faster effects than Retinol

• Chemically less stable, harder to formulate

HPR Molecular Structure

HPR (Hydroxypinacolone Retinoate)

• Acts directly with minimal conversion

• Immediate results upon application

• Less irritating and more stable, considered a 4th-generation retinoid

Clinical Evidence (AMWC 2025, Monte Carlo)

According to a study presented at the 2025 Monte Carlo International Conference, 42 participants applied a 0.2% concentration of the same skincare formulation for 4 weeks.

The results showed that no single ingredient was overwhelmingly superior; instead, each retinoid demonstrated strengths in different areas.

Efficacy Comparison: Retinal / Retinol / HPR

Key takeaway: Each retinoid targets slightly different aspects, no single retinoid is universally “best.”

⚠️ Retinoid Usage Guidelines

1. Start low & slow: Begin with low concentrations 2–3 times per week in the evening. Avoid daily use at first.

2. Expect dryness or irritation: Apply moisturizer after retinoids; sensitive skin may benefit from mixing with a cream.

3. Always wear sunscreen: Retinoids temporarily increase UV sensitivity. SPF 30+/PA+++ is essential.

4. Avoid after procedures: Wait 5–7 days after lasers or peels until your skin barrier recovers.

5. Avoid during pregnancy & breastfeeding: Vitamin A derivatives are not recommended. See Safe Skincare During Pregnancy

Choose the Right Retinoid for Your Skin

Accurate skin type and condition analysis is crucial before selecting a retinoid. Misuse can cause irritation or barrier damage.

At Repic Clinic, we use advanced diagnostic tools — MarkVu & MetaVu— to assess:

• Pores and texture

• Skin barrier function

• Redness and pigmentation

• Moisture & sebum balance

• Aging progression

These analyses guide personalized skincare and retinoid selection, the first step toward healthier skin.

Summary

We’ve explored:

• Retinoid basics

• Differences between Retinol, Retinal, HPR

• Effects backed by clinical research

• Skin-type-specific selection and precautions

Vitamin A derivatives are powerful yet precise tools for skin improvement. Personalized application based on skin type and condition ensures maximum benefits with minimal risk.

Repic Clinic will continue providing practical, evidence-based skincare advice to help your skin stay healthy.

FAQ: Retinoids in Skincare (Retinol, Retinal, and HPR)