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How to Use Glycolic Acid for Your Skin to Maximize the Benefits

Glycolic acid, a well-loved tool in the arsenal for skin rejuvenation, has gained popularity for at-home use over the last several years and is not slowing down anytime soon. Gentle exfoliation that reveals smoother, plumper, clearer, and brighter skin without days of downtime is an irresistible addition to any skin regimen. However, in the case of glycolic acid, there can be too much of a good thing. Overuse and misuse can lead to the irritation that we seek to avoid. Learning how to use glycolic acid safely is crucial to unlocking its potential without compromising skin health.

What is glycolic acid?

Glycolic acid belongs to the alpha hydroxy acid (AHA) class of carboxylic acids used for exfoliation. Other AHAs include lactic acid, mandelic acid, and citric acid. AHAs are usually colorless, odorless, and hydrophilic in nature ('water-loving') and are thus able to dissolve in water easily. They are derived from naturally occurring substances, such as fruit and milk. As the name suggests, glycolic acid is derived from a carbohydrate, specifically from sugar cane. Glycolic acid is the smallest alpha hydroxy acid and the most widely used.

How does glycolic acid work in the skin?

The skin is made of three main layers. The deepest layer, the hypodermis, is mostly composed of fat and acts as a cushion for our body. It also has the roots of hair follicles. The middle layer, the dermis, is where the skin's collagen resides. It also contains glands and nerve endings. The dermis provides structure to the skin and acts in regulating body temperature and sensing touch. Blood and lymphatic vessels, as well as nerves, are also found in the dermis and hypodermis.

The uppermost layer, the epidermis, is further divided into five layers. The innermost layer of the epidermis, stratum basale, contains skin cells called proliferating keratinocytes that divide to create new skin cells. These cells move up the layers as new cells are formed and undergo the normal aging process, which changes their structure and function. This process describes the natural skin cell turnover. By the time the keratinocytes are a part of the most superficial layer, stratum corneum, they have undergone natural cell death and have stopped their previous metabolic activity.

Three main layers of skin

This layer of dead keratinocytes provides protection to the layers of live keratinocytes and other skin cells below from pathogens and environmental insults. They remain attached to each other and the cells below through chemical bonds and lipids until more keratinocytes die or there is natural exfoliation in response to the environment.

Glycolic acid, like the other AHAs, is a keratolytic agent. It breaks down the connections between keratinocytes in the stratum corneum. This dissolution prompts cellular turnover of the epidermis by exfoliating some of these dead cells, allowing the newer layers of the skin to show through.

As glycolic acid is a smaller molecule, it can penetrate further into the skin than other AHAs. In addition, glycolic acid does not self-neutralize and, without neutralization, will continue to penetrate into the skin. Neutralization can be done with water or basic solutions that contain sodium bicarbonate or sodium hydroxide. Deeper penetration allows the glycolic acid to reach the dermis, but prolonged exposure to glycolic acid also increases the risk of irritation.

What glycolic acid concentration can be used at home?

In-office glycolic acid chemical peels are usually available at 20–70%, with initial peels starting at 20% and gradually increasing at subsequent visits if tolerated well.

Although commercial glycolic acids available for at-home use are of a lower concentration, they should be used similarly, starting at the lowest concentration for a few minutes and gradually increasing to the recommended time of contact and concentration as tolerated to avoid complications. Home-use products start at 5%, with most formulations containing 5–10% glycolic acid. Higher concentrations are also available for at-home peels and must be used cautiously by those whose skin is accustomed to glycolic acid exposure.

In addition to concentration, the pH of the glycolic acid also has a considerable influence on its efficacy.

Cosmetic companies offer glycolic acid at different concentrations and in varying formulations. However, cosmetic products are not regulated like prescription drugs, and companies do not run standardized clinical trials. Thus, the actual amount of the product absorbed by the skin and the effect of its formulation can provide varied results and side effects.

Always consult a professional if there are adverse effects after using glycolic acid. A dermatologist can also help determine if you are a suitable candidate for glycolic acid and help you choose the right product for your skin type and concerns.

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What are the benefits of glycolic acid for the skin?

Glycolic acid’s benefits have been most studied for cosmetic effects on the skin. There is evidence for several ways it can help improve the structure and appearance of the skin when used appropriately:

  • Exfoliation. By exfoliating the stratum corneum — the outermost layer of the skin — glycolic acid decreases the number of dead keratinocytes. While these cells are an important component of the skin barrier, the natural turnover of the epidermis decreases as we grow older, causing the skin to have an uneven texture and appear dull. Keratinocytes of this layer can also clump abnormally, blocking pores and leading to acne. Exfoliation further helps the skin appear even by removing superficial hyperpigmented cells caused by pigmentation disorders.
  • Improvement of hyperpigmentation. In addition to exfoliating the superficial hyperpigmented cells, glycolic acid may inhibit the formation of melanin and assist in treating melasma, hyperpigmentation caused by photoaging, and post-inflammatory hyperpigmentation.
  • Hydration. As glycolic acid is hydrophilic, it draws water to itself, acting as a humectant when applied to the skin. It has also been found to increase the amount of hyaluronic acid in the skin. This makes it a chemical exfoliant for those prone to dry skin.
  • Antibacterial effects. There is evidence that at a pH of 3.5, even low concentrations of glycolic acid can destroy the acne-causing bacteria Cutibacterium acnes.
  • Anti-aging effects. The production of collagen and elastin, connective tissue proteins that help structure our skin, slows down as we age. Normal physiological function, as well as environmental factors, such as UV light and stress, break down the collagen already there, but we don’t make enough to replace what is being lost. This leads to an overall loss that causes skin sagging and wrinkling. Glycolic acid has been found to increase the amount of collagen in the second main layer of the skin (dermis) at a pH of 4, even at lower concentrations, and improve the quality of elastin fibers.

Other benefits of glycolic acid

Along with its popularity for facial skin rejuvenation, glycolic acid has been touted to treat many other dermatologic concerns.

  • Bacne. As bacne (trunkal acne) has a similar pathomechanism to acne, glycolic acid may be an effective treatment. There are glycolic acid-based exfoliants designed for the body which may be used.
  • Body hyperpigmentation. Darkening of the skin in other parts of the body usually results from thickening of the epidermis, which may have different pathomechanisms. The skin in areas of high friction, such as the knees, elbows, and between the thigh, often thickens as a protective mechanism in response to friction (hyperkeratosis). Acanthosis, a darkening caused by thickening in skin folds like the armpits, the groin, and the back of the neck, may be caused by diabetes, hormonal dysfunction, or medications. As glycolic acid increases skin turnover, it may help with hyperpigmentation caused by skin thickening. However, it is not very effective for acanthosis, which may require further medical investigation. In addition, applying glycolic acid to skin folds can occlude the product and increase the risk of irritation.
  • Ingrown hair. Ingrown hair occurs when the hair curves back and grows into the skin. It is associated with shaving, plucking, tight clothing, and curly hair. Glycolic acid helps thin the skin covering the hair and may also penetrate the shaft and make the hair straighter, helping it grow out.

Caution should be used as the research on these potential indications is limited. Consulting your healthcare professional for these concerns can also help provide more treatment options.

How to maximize the benefits of glycolic acid

The many benefits of glycolic acid can significantly boost the skin’s appearance and health when used correctly.

Start slow, then grow

While many product labels recommend daily use, it is safer to introduce glycolic acid once a week at the lowest concentration for a few minutes. If your skin tolerates this, increase the time of exposure until you reach the recommended limit provided on the product label.

Before using a new product, patch test on the inside of the forearm to prevent more significant side effects in case of allergy or sensitivity to any ingredients.

Once your skin is comfortable with the new product, the concentration may be increased to obtain a more potent effect.

Each person’s requirement for exfoliation is different. For most, daily exfoliation is unnecessary and may damage the skin barrier. The resultant inflammation is detrimental to the overall skin structure and should be avoided.

How should glycolic acid be used?

The hydrophilic nature of glycolic acid makes it harder to absorb if the skin is oily. Application on clean, dry skin is recommended to ensure efficacy. The exfoliant effect of glycolic acid leaves the skin more vulnerable to photodamage from UV rays. While there is no specific best time to use glycolic acid, fitting it into a nighttime skincare regimen is usually easier and reduces the risk of UV damage. Use a lotion or moisturizer after using glycolic acid to avoid dehydrating the skin.

How often should glycolic acid be used?

Glycolic acid should not be used multiple times a day in the same area as it can lead to over-exfoliation.

As higher concentrations of glycolic acid have greater efficacy deeper in the skin, it may be more advantageous to gradually work up to a higher tolerable concentration that is used weekly rather than using a low concentration multiple times a week. In cases where glycolic acid is only used for superficial skin turnover, low concentrations may be used safely up to 5 times a week. While using glycolic acid less often than recommended on the product packaging may be safe, the recommended upper limit should be strictly adhered to.

Sunscreen: a necessary companion for exfoliating acids

Exfoliating acids may diminish acne, smooth fine lines and wrinkles, thicken collagen, and give us glowing skin. However, they also reduce our natural barriers to environmental insults.

Glycolic acid, like all exfoliating acid, increases the risk of exposure to UV rays, which not only cause photoaging but also increase the risk of sunburn and skin cancer. In addition, damage to cells by UV exposure can increase the risk of hyperpigmentation, especially in those with darker skin tones. It is imperative that the use of exfoliating acids is accompanied by applying sunscreen the next day if the acid is used at night, if not every day, to reduce the risk of adverse effects. If glycolic acid is used during the day, sunscreen should be the last step of skincare.

Given the variety of sunscreen available, it can be confusing as to which sunscreen to use. The most important thing is choosing a broad-spectrum sunscreen with a minimal SPF of 30, which you will use consistently and adequately. Sunscreens degrade with time, so don’t forget to reapply every two hours.

In addition to sunscreen, wearing broad-brimmed hats and sun-protective clothing can provide further protection.

Choosing the right glycolic acid

The formulation of the glycolic acid, your skin type, and the concerns you want to address should guide choosing the product you will use.

Glycolic acids are available in formulations for nearly every skincare step, making them easy to incorporate into a skincare regimen for most people. Avoid using more than one type of glycolic acid product to prevent irritation.

  • Cleansers. Ideal for more regular use and introducing glycolic acid as they are usually created to be gentle.
  • Toners. For application after cleansing to address skin texture and refine pores. Toners can also come as a pad for convenience.
  • Serums. May contain higher concentrations and other skincare ingredients to target specific concerns, such as hyperpigmentation and fine lines.
  • Peels. Suited for periodic use. Peels are usually more potent and used for deeper exfoliation, more dramatic results, and to target the dermis to stimulate collagen. These should be used once a week or less. Introduce peels at the lowest concentration until your skin acclimatizes. However, this does not mean you should use peels that cause inflammation and irritation.
  • Moisturizers. Often combine glycolic acid with hydrating ingredients and may be appropriate for frequent use as long as tolerated.

With such a variety of options available, choosing the right product to start your glycolic acid journey can be daunting. You can use the table below as an initial guide.

Skin typeConcentrationRecommended product typeNotes
Dry5–10%Cleansers, moisturizers, serumsLook for products with hydrating ingredients, such as hyaluronic acid.
Oily5–10%Cleansers, toners, serums, peelsChoose oil-free products.
Combination5–10%Cleansers, toners, serumsAim to balance hydration and exfoliation. Consider using different products on dry and oily areas.
Sensitive5%Cleansers, moisturizersStart at the lowest concentration. Patch test prior to use.

Can glycolic acid be used with other acids?

Combining glycolic acid with other skincare ingredients can be confusing. Some can precipitate dermatitis by provoking an inflammatory response. Others can enhance your routine. Remember to introduce active ingredients to your skincare regimen one at a time and patch test before use. Combining products with caution and following the instructions on the product label is essential to minimize side effects.

Glycolic acid and other exfoliating acids

Using glycolic acids with other AHAs, such as lactic acid and mandelic acid, is not recommended as this can increase the risk of over-exfoliation.

Some products combine glycolic acid with lactic acid, a beta hydroxycarboxylic acid (BHA), which is hydrophobic ('water-fearing') and soluble in oil. It can be an ideal combination as BHAs target the excess sebum in pores. However, this combination can be irritating for some. It is also not recommended to use separate formulations containing each acid together and should rather be used on different days to reduce the risk of side effects.

Glycolic acid and retinol

Glycolic acid and retinol are popular skincare ingredients for their significant long-term benefits to the skin. While they have individual advantages, they increase the turnover of the topmost layer of the skin through differing mechanisms of action. When used together, glycolic acid and retinol can cause irritation and increase the skin’s vulnerability to UV damage. You may incorporate them into your regimen by using them on different nights. However, if irritation occurs, you may have to choose one product or decrease the concentration of one or both products. Sunscreen should be used during the day to protect the skin.

Glycolic acid and vitamin C

Topical vitamin C is used in skincare as an antioxidant and for treating hyperpigmentation. Those with sensitive skin should avoid using glycolic acid and vitamin C together. Those with more resilient skin may be able to layer them together, but this should be done with caution as there is a risk of irritation. The ideal way to use glycolic acid and vitamin C is to use them during different times of the day. Vitamin C can protect against free radicals caused by UV radiation and environmental pollutants during the day, and glycolic acid can be used safely at night for exfoliation.

Glycolic acid and azelaic acid

Azelaic acid is considered a 'super ingredient' in skincare due to its minimal side effects and many dermatological benefits, including decreasing hyperpigmentation and its anti-inflammatory, antibacterial, and antioxidant properties. Layering azelaic acid after using glycolic acid can augment its absorption and is safe for most. If you experience irritation or have sensitive skin, use them at different times of the day — azelaic acid in the morning and glycolic acid at night.

Glycolic acid and hyaluronic acid

Hyaluronic acid is a naturally occurring carbohydrate-based molecule found in different parts of the body, including the skin. It is a potent humectant often used in cosmetics for its hydrating properties. Hyaluronic acid is an ideal skincare ingredient to layer after using glycolic acid, as it can counteract any dryness and help bolster the skin barrier.

Side effects of glycolic acid

Glycolic acid is not likely to produce side effects when used correctly and if you are not allergic to it. Those with sensitive skin may still have some irritation when beginning a regimen at the lowest concentration. In most cases, once your skin becomes accustomed to it, you will no longer have any side effects. If you are concerned about how your skin will tolerate glycolic acid, a dermatologist can guide you in choosing the right product for your skin type and concerns.

When overused, used without regular sunscreen, or combined with other potentially irritating skincare ingredients, glycolic acid may cause side effects, including:

  • Sun sensitivity and sunburn
  • Redness and irritation
  • Dry, flaking skin
  • Hyperpigmentation
  • Itching
  • Burning
  • Soreness or tightness

If you experience mild irritation or flaking, you can try to decrease the glycolic acid concentration to one you were comfortable with previously. Discontinue use immediately and consult your dermatologist if you experience severe side effects or if mild side effects do not subside after decreasing concentration or discontinuing a product.

Glycolic acid and pregnancy

The safety of glycolic acid in pregnant people has not been established, however, glycolic acid products with concentrations less than 10% are considered to be safe during pregnancy as they are minimally absorbed through the skin. However, it is recommended that you check with your obstetrician before using any products during pregnancy, as some animal studies have shown adverse reproductive effects when glycolic acid is administered systemically. However, the doses in the trials were much higher than those used in cosmetic products.

Another consideration is the changes that occur to your skin during pregnancy. You may find that the products you tolerated before pregnancy may irritate your skin during pregnancy.

Who should not use glycolic acid?

While glycolic acid may benefit most people, not everyone can tolerate it.

Glycolic acid should not be used in cases of:

  • Previous allergic reactions to glycolic acid products
  • Sunburns
  • Open wounds
  • Active eczematic flares

Glycolic acid's versatility in treating multiple skin concerns and its relatively safe side-effect profile have made it a popular ingredient in skincare and increased its use in home skin treatments. It has been adapted for use in different skin care steps and can be added to the regimen for people with all skin types. As it is an exfoliant, using it with other actives in the skin care regimen should be done with caution. It should also be used conservatively as overuse may cause inflammation and irritation, the damage of which may outweigh any benefits afforded by glycolic acid. Regular sunscreen use and sun-protective clothing can prevent UV damage as glycolic acid increases photosensitivity. If you are unsure if glycolic acid is right for you or don't know where to start, consult a dermatologist for recommendations.

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