AHA vs BHA: A Beginner’s Guide To Chemical Exfoliation

Exfoliation is one of the most common steps in a skincare routine. It helps remove the build-up of dead skin cells so the skin surface looks fresher and more refined. Many people choose to exfoliate because it supports skin that looks and feels smoother and allows other skincare products to sit more evenly on the surface. However, with the wide variety of products available today, it can be confusing to know which options may suit you.

This guide explores what AHAs and BHAs are, how they differ, how they can be incorporated into a skincare routine and what you should keep in mind if you are considering products that contain them. Whether you are comparing AHA vs BHA exfoliant options or simply wondering when to use AHA vs BHA, we’ll help you understand the basics.

What are AHAs?

Alpha hydroxy acids (AHAs) are a group of water-soluble acids, usually derived from natural sources such as fruits, sugar or milk. They work at the surface of the skin by loosening the bonds that hold dead cells together. This gentle shedding process aims to help you achieve a smoother and more radiant-looking appearance.

Commonly used AHAs include:

• Glycolic acid — A small-molecule AHA often chosen to address uneven skin texture.
• Lactic acid — A milder option that also supports hydration on the surface of the skin.
• Mandelic acid — A larger-molecule AHA that’s considered gentler and slower-acting, sometimes recommended for sensitive skin types.

Because they act on the outer layer, AHAs are often included in exfoliators and masks or other surface-smoothing treatments designed to address the appearance of dullness, roughness or uneven tone.

What are BHAs?

Beta hydroxy acids (BHAs) differ from AHAs because they are oil-soluble. This allows them to pass through surface oils and into pores. Like AHAs, they also exfoliate the outer skin layer, but their ability to interact with oil makes them commonly used in cosmetic products for oilier skin types.

The best-known BHA is salicylic acid. It has been widely used in cosmetic formulations to minimise the look of pores and reduce surface congestion. Because of their oil solubility, BHAs are frequently found in formats such as serums and tonics, which are applied directly to the skin several times per week.

Key differences: AHA vs BHA

When it comes to AHA acid vs BHA, the two categories target slightly different concerns:

• AHAs — Work mainly on the skin's surface, managing the look of dullness and rough patches and supporting a smoother and more radiant finish.
• BHAs — Can travel into pores, targeting the appearance of oiliness and surface build-up, which may make your complexion look clearer and brighter.

Because of these differences, some people incorporate both into their routines. For example, an AHA cleanser might be used a few times a week, while a BHA tonic is alternated on other days.

When to use AHA vs BHA

Choosing between the two often comes down to skin type and main concerns:

• Normal to dry skin — May respond well to AHAs, which support surface hydration and smoothing.
• Combination to oily skin — Often benefits from BHAs, which can help minimise the appearance of large pores and blemishes.
• Mixed concerns — Some people alternate between AHAs and BHAs to address multiple needs.

Another factor to consider is sun sensitivity. Both AHAs and BHAs can increase the skin's reactivity to sunlight. For this reason, they are usually applied in the evening, with sunscreen in the day. Some people also turn to direct acids for higher-strength options, but these should be introduced carefully.

Tips for a safer introduction

When starting with chemical exfoliants, a cautious approach is best:

• Begin with a low-strength formulation.
• Introduce the product once or twice a week and increase gradually if your skin tolerates it well.
• Avoid layering multiple acid-based products in the same routine.
• Pair exfoliants with moisturisers to help maintain comfort.
• If irritation occurs, reduce frequency or stop use.

Exfoliation is only one part of a balanced skincare routine. Other steps, such as using cleansers and toners, hydrating products and daily sun protection, all contribute to maintaining skin health and comfort.

Discover Medik8's range of skincare

If you're ready to explore exfoliation, Medik8 offers a range of options to suit different routines. Surface Radiance Cleanse pairs AHAs and BHAs in a refreshing gel cleanser, while Press & Clear provides gentle-release salicylic acid. For the body, the Smooth Body Exfoliating Kit is designed to smooth the feel and appearance of skin texture.

Shop the full Medik8 collection and find the right exfoliant to help support your skincare journey.

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