One of my readers contacted me asking me what a BHA serum is.
Firstly, a serum is a skincare product more highly concentrated in its active ingredients than a moisturizer or treatment cream. You would normally use a serum before your moisturizer to spot treat a particular problem, such as pigmentation, pimples, blackheads or wrinkles.
A BHA serum contains Beta Hydroxy Acid. The most common BHA in skin care is salicylic acid. Salicylic acid can be derived from the bark of the Willowtree or more commonly is made synthetically. Salicylic acid is an oil soluble acid, and is also related to aspirin. It is a very strong acid, and in skin care only a maximum of 2% is used.
Because it is an oil soluble acid, it is attracted to the oils in the skin such as the oil trapped deep inside the clogged pores and blackheads. Oil dissolves oil, so this acid is best used on an oily skin with problems such as clogging, congestion, milia and blackheads. It is well known for its ability to penetrate deep inside the pores and exfoliate the pores from the inside out, helping to clear impurities and improve a problem skin.
As it is related to aspirin, it has powerful anti-inflammatory action on the skin. This is very beneficial for skins suffering with acne and inflammation. However people with aspirin allergy should do a patch test behind the ear to make sure they can use it without causing allergies.
Salicylic acid is also a very good keratolytic. This means it is very efficient at breaking down dead cells as it targets the keratin found in the dead cells of the skin. This makes it a very good exfoliant both inside of the pores and on the surface of the skin. Not only does it help to improve blackheads but it's also very good at helping improve open pores, milia, thickened skin, sun damage, wrinkles and pigmentation.
Salicylic acid works best at lower doses from 1 to 2% at a pH of 3 to 4. Just like all acids, it works best in a serum or a moisturizer. Using AHAs or BHA in a cleanser is more gentle because the acids are not left on the skin to penetrate. So if you use a cleanser with AHAs or BHA, leave it on for a few minutes in order for the acids to do their work efficiently. For more problematic skin, my advice is use either a serum or a moisturizer with a BHA and only use it at night on your skin. Using multiple products on your skin with BHA could potentially cause side-effects such as rashes, irritations and excessive dryness and flaking of the skin, so don't over do it.
All AHAs and BHA overtime thin your skin and make it more sensitive to the sun, so you must protect your skin. If you're using AHAs or BHA in your skincare routine you must also use a broad spectrum sunscreen to protect your skin during the day.