Glycolic acid is one of the most popular and well-studied skincare ingredients available. It is best known for resurfacing, exfoliating and smoothing the skin. This is why it appears in so many cleansers, toners, serums and peels. As an over-the-counter active, it is easy to add to a routine and gentle enough for most people when used correctly. However, like any acid, it works best when you understand what it does and how to use it safely. In this article, we explore what glycolic acid is and what it does for your skin. We also look at how it compares to other acids and how to use it without irritation.
What is Glycolic Acid?
Glycolic acid belongs to a group of chemicals known as alpha hydroxy acids (AHAs). It is derived from sugar cane and is the smallest molecule in the AHA family. This small size is what makes it so effective. It allows glycolic acid to penetrate the surface of the skin easily and work quickly. Other AHAs you may have come across include lactic acid from milk and citric acid from fruit. Glycolic acid works by loosening the bonds that hold dead skin cells together. This helps the skin shed those cells and encourages the regeneration of fresh ones underneath. With regular use, it also supports collagen production, which is part of why it is so popular for ageing and uneven skin.
What Does Glycolic Acid Do for Your Skin?
Glycolic acid is a true multitasker and suits a wide range of skin concerns. Its benefits come mainly from gentle, consistent exfoliation. The main benefits include:
- Exfoliation and smoother texture: By dissolving the bonds between dead skin cells, glycolic acid leaves the surface smoother and more refined. This makes it useful for rough or uneven texture and dull, flaky skin.
- Brighter, more even tone: Regular use helps fade dull patches and hyperpigmentation. It does this by speeding up cell turnover so pigmented cells are shed more quickly.
- Fewer fine lines: Because it supports collagen, glycolic acid can soften the appearance of fine lines. Over time, it also gives ageing skin a fresher, plumper look.
- Clearer, less congested skin: Its exfoliating action helps keep pores clear, which makes it helpful for blackheads, congestion and oily skin. For active acne, it is usually best combined with other ingredients.
- Better product absorption: By removing the build-up of dead cells, glycolic acid helps the rest of your routine absorb more effectively. This includes hydrating ingredients like hyaluronic acid.
What’s the Difference Between Glycolic Acid and Other AHAs?
Glycolic acid is just one of several alpha hydroxy acids used in skincare. The main difference between them is molecule size, which affects how deeply they work. Glycolic acid is the smallest, so it penetrates the most deeply and tends to give the most dramatic results. Lactic acid is larger and gentler, which makes it a better choice for sensitive or dry skin. Mandelic acid is larger still and milder again. There are also beta hydroxy acids like salicylic acid, which are oil-soluble and better suited to clogged pores and oily skin. If you are not sure which exfoliating acid is right for you, match the acid to your skin type and concern.
How Do You Use Glycolic Acid in Your Routine?
Glycolic acid is easy to add to a routine, but a slow and steady approach gives the best results with the least irritation. It comes in several forms and strengths, so you can choose one to suit your skin. Here is how to use it well:
- Choose the right strength: Over-the-counter products usually contain glycolic acid at up to around 10%. Stronger professional chemical peels reach much higher concentrations and are carried out by trained practitioners.
- Start with a gentler format: Cleansers and toners rinse off or contain lower concentrations, so they are a good starting point. Leave-on serums and at-home peels are stronger and best introduced once your skin has adjusted.
- Build up slowly: Begin one to two nights a week and gradually increase as your skin tolerates it. This helps you avoid irritation and a damaged skin barrier.
- Apply at night: Glycolic acid is best used in the evening. It can break down in sunlight and it also makes the skin more sensitive to UV.
- Avoid stacking strong actives: Using glycolic acid on the same night as retinoids or other acids can cause too much irritation. Alternate them on different nights instead.
- Always follow with sunscreen: Because glycolic acid resurfaces the skin, the fresh skin underneath is more vulnerable to sun damage.
What are the Side Effects of Glycolic Acid?
Glycolic acid is well tolerated by most people, but it is still an active acid. Used too often or at too high a strength, it can irritate the skin. The main things to watch for are:
- Irritation and dryness: Redness, stinging, peeling and dryness are the most common issues, especially when you first start or use it too frequently. Reducing how often you use it usually settles this.
- Increased sun sensitivity: AHAs like glycolic acid make the skin more sensitive to UV light. Daily broad-spectrum SPF 30 or higher is essential, and you should avoid tanning beds.
- Not always suitable for sensitive skin: Those with very sensitive, reactive or compromised skin may find glycolic acid too harsh. A gentler acid like lactic acid or a supportive ingredient such as niacinamide may suit better.
- Patch test first: Always patch test a new product on a small area before applying it more widely. This helps you check for any reaction.
Is Glycolic Acid Safe for Skin of Colour?
Glycolic acid can work very well for skin of colour, but it needs a more careful approach. Deeper skin tones have more active melanocytes, so any irritation can trigger post-inflammatory hyperpigmentation. This is the dark mark that can linger after inflammation settles. The irony is that glycolic acid is often used to treat that very problem. In fact, serial glycolic acid peels have improved post-inflammatory hyperpigmentation in darker skin. This was shown in patients with Fitzpatrick types IV to VI, with minimal side effects. The risk comes from overuse rather than the acid itself. To use it safely on deeper skin tones, a few principles help:
- Start low and go slow: Use lower concentrations and only a couple of nights a week. Daily use or high-strength products bought online are the most common cause of problems.
- Avoid double exfoliation: Do not combine glycolic acid with a physical scrub or another acid on the same day, as this stacks up irritation.
- Consider a gentler acid: Mandelic acid and lactic acid are larger, milder molecules that often suit reactive deeper skin tones better.
- Be strict with sun protection: Daily SPF matters even more here, as UV exposure drives further hyperpigmentation.
If your hyperpigmentation is persistent or stubborn, it is worth getting advice rather than escalating strengths on your own.
Can You Use Glycolic Acid During Pregnancy?
If you are pregnant, glycolic acid needs a more cautious approach. Concentrations above 10% are not considered safe during pregnancy, so higher-strength products and professional peels are best avoided. Lower-strength over-the-counter formulas are less of a concern, but many people prefer to switch to a gentler acid during this time. Lactic acid is considered safe in over-the-counter strengths and makes a good stand-in for glycolic acid. As always, it is sensible to check with your doctor or midwife before using any acid in pregnancy.
Glycolic acid is a brilliant all-rounder for smoother, brighter and more even skin. The key is to start gently, use it consistently and protect your skin from the sun. For deeper concerns like stubborn hyperpigmentation, melasma or skin ageing, glycolic acid is rarely enough on its own. It works best as part of a wider plan that may include prescription-strength actives.
At City Skin Clinic, we are passionate about personalised skincare. Our online clinic offers safe and effective treatments using ingredients like tretinoin and hydroquinone where appropriate. Our doctors treat skin conditions like acne, hyperpigmentation, melasma and skin ageing. To start your personalised plan, book a virtual video consultation or use our online consultation form. The journey towards great skin and hair starts here.
This article is intended for general informational purposes only and is not a substitute for medical advice, diagnosis or treatment. Always consult a qualified medical professional with any concerns about your skin or treatment options.
