One of the most coveted skincare products, retinol serums are available everywhere.
A derivative of vitamin A, the over-the-counter treatment is primarily used to treat acne and age-related skin concerns.
Here's everything you need to know about the popular retinoid treatment.
What Is Retinol and How Does It Work?
Retinol is the strongest retinoid available over-the-counter. Other types of retinoid like tretinoin typically require a prescription from your dermatologist.
It's a topical treatment derived from vitamin A which is a key nutrient when it comes to boosting skin renewal and collagen production.
While other skincare products targeting age related concerns will typically exfoliate and remove dead skin cells, the smaller molecules that make up a retinol instead go deep beneath the outer layer of skin to your dermis.
This neutralizes free radicals and gives a skin plumping effect by promoting production of elastin and collagen.
Founder of skin treatment Million Dollar Facial, Jenna Unwin told Newsweek: "When retinol is absorbed into the skin, enzymes convert retinol to retinoic acid which encourages the production of new skin cells, allowing skin imperfections such as sun damage, hyperpigmentation and fine lines to gradually fade away.
"Once absorbed and converted to retinoic acid, collagen, elastin and hyaluronic acid levels increase."

What Is Retinol Used For?
Many use retinol to tackle signs of aging like wrinkles, fine lines, and sun spots.
In addition to being a potent anti-aging treatment, retinol is also used for treating severe acne and associated scarring.
It keeps your pores unclogged by preventing the formation of blemishes, though it typically takes six to 12 weeks to see an improvement in acne when using retinol.
They can also be used to treat melasma, hyperpigmentation, and uneven skin texture.
What Age Should I Start Using Retinol and Who Can Use It?
It's generally recommended to begin adding retinol into your skincare routine when you are in your mid 20s to early 30s.
Their use is not recommended during pregnancy as they may cause birth defects or miscarriage.
Retinols may also aggravate eczema and should not be used when you have an active eczema rash.
How Do I Use Retinol?
Retinols can be irritating to the skin when you first start using them so it is often recommended to begin with a lower concentration.
You should introduce it to your skincare routine by first only applying a few nights a week, building up to every night.
Retinol application should be followed by moisturizer, or if your skin is particularly sensitive, you could try the "buffering method" and apply your moisturizer before your retinol to protect against irritation.
You could also try waiting at least 30 minutes after washing your face to apply your retinol to reduce the potential for irritation.
"Retinol is best applied before bed, with the application of SPF the next morning," Unwin said.
"As a rule, when using retinol it's important to make sure you are using SPF50 since retinol can make your skin more sensitive to UV rays which in turn can make your skin more prone to sun damage."
What Are the Side Effects of Using Retinol?
As it can be very irritating to the skin, it is common to experience dryness, itchiness, flakiness or redness, especially when first starting to use retinol.
These tend to be temporary and improve within a few weeks once your skin has become used to the product.
If this persists, it may be worth considering using a lower concentration.
Should I Get a Retinoid Prescription?
If you're not seeing results from using drug store products, it may be worth considering speaking to your doctor.
Stronger retinoids are available on prescription including tazarotene and tretinoin which both target wrinkle and fine lines, and adapalene and isotretinoin can be used to treat acne.
These are stronger than the over the counter retinols available for purchase so be sure to follow your doctor's advice when using them and always apply sunscreen the following morning.