Lactic acid is an alpha hydroxy acid (AHA) derived from sour milk, though it can also be synthesized in a lab. It’s a popular ingredient in skincare products for its ability to effectively exfoliate the skin and improve its overall texture and tone.
Lactic acid first known use dates back to ancient Egypt, where sour milk was used in skincare for its beautifying effects. Cleopatra, famous for her beauty rituals, is often cited as having bathed in sour milk to maintain her youthful complexion. However, the scientific understanding of lactic acid and its benefits was still millennia away.
The term “lactic acid” comes from “lac”, the Latin word for milk, as this compound was first isolated from sour milk. The Swedish chemist Carl Wilhelm Scheele was the first to isolate lactic acid in 1780. At the time, Scheele was working on the properties of various types of milk, and he discovered lactic acid as part of his investigations. He noticed that when milk turned sour, it produced a new substance, which he was able to isolate and identify as lactic acid.
In the 1800s, French scientist Louis Pasteur discovered the role of microorganisms, specifically lactic acid bacteria, in the fermentation process. His work demonstrated that these bacteria produce lactic acid as a byproduct when they ferment lactose, the sugar found in milk.
However, it wasn’t until the 20th century that the skincare benefits of lactic acid were scientifically explored and understood. It was recognized that lactic acid, as an alpha-hydroxy acid (AHA), could help in exfoliation, improving skin texture, and boosting hydration. Since then, lactic acid has become a staple in many skincare products, from cleansers to peels.
In the 21st century, lactic acid is produced synthetically for use in skincare products. It is also used in a wide range of other industries, including food and beverage, where it serves as a preservative and flavoring agent, and in medicine, where it is used in various diagnostic tests and treatments.
Lactic acid is also found in many skincare products. Lactic acid has a number of benefits for the skin, including:
- Exfoliation: Lactic acid works by breaking down the bonds between dead skin cells, allowing them to be easily removed. This leads to smoother, brighter skin.
- Hydration: Unlike other AHAs, lactic acid also has moisturizing properties. It helps increase the skin’s natural hydration levels by stimulating the production of ceramides, a type of lipid that helps the skin retain moisture.
- Skin Lightening: Lactic acid can help fade hyperpigmentation, age spots, and sun damage, leading to a more even skin tone.
- Stimulation of Collagen Production: Regular use of lactic acid can stimulate the production of collagen, leading to firmer, plumper skin.
- Improvement of Skin Texture: By promoting cell turnover, lactic acid can help reduce the appearance of fine lines and wrinkles.
When incorporating lactic acid into treatments, it’s essential to start with a lower concentration to see how the client’s skin reacts. Lactic acid products typically come in concentrations ranging from 5% to 30%.
A patch test is recommended before using any new product on a client to check for any adverse reactions. Apply a small amount of the product containing lactic acid to a discreet area of the client’s skin, like behind the ear or the inside of the forearm. Wait 24 hours to see if there are any signs of irritation or allergic reaction.
As lactic acid can make the skin more sensitive to the sun, advise clients to always use sun protection during the day, even if the treatment was applied at night.
Potential Side Effects
While lactic acid is generally well-tolerated, especially given its hydrating properties, some people may experience redness, peeling, or a stinging sensation, particularly at higher concentrations. Clients with sensitive skin or skin conditions like rosacea or eczema may be more prone to these side effects.
If a client reports any discomfort, consider using a lower concentration or reducing the frequency of use. In some cases, it may be necessary to discontinue use entirely.