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So you heard about all its major benefits, and now you're wondering when to start using retinol. The powerful skin care ingredient is known for treating acne, smoothing fine lines and wrinkles, and improving overall skin texture -- but how do you know it's time to add it in your routine?

First, it's important to understand what retinol actually is. Retinol is a term used for topical skin care products that contain a vitamin A derivative. Used in serums, face creams, and eye creams, retinol is a type of retinoid.

"Retinoids work by increasing collagen production, as well as increasing the rate of skin-cell turnover," says Shari Marchbein, MD, a board-certified dermatologist in New York City. "Retinol helps treat acne, clogged pores, and blackheads by reducing the stickiness of the cells that clog pores, as well as speeding up the rate at which the skin turns over and regenerates."

Want to get in on these skin care benefits? Ahead, we asked board-certified dermatologists everything you need to know, including when to start using retinol, how to add it to your routine, and more.

According to Kiran Mian, MD, a board-certified dermatologist at Hudson Dermatology & Laser Surgery in New York City, retinol use comes down to a few factors. "To treat active acne, I recommend starting a retinoid right away," Dr. Mian says. You can also start as early as needed: "There are gentle options available like adapalene that are appropriate for teenage skin."

If you're looking to combat signs of aging, Dr. Mian recommends starting in your mid 20s. "After age 25 you start losing collagen and the rate of loss increases with age. Other factors that contribute to this rate are sun exposure, stress, smoking, poor diet, and inadequate sleep."

Sensitive skin

"For those with dry or sensitive skin, I like encapsulated retinols, like Biossance Squalane + Retinol Night Serum," Dr. Mian says. "This one is time released, allowing for slow exposure to retinol, minimizing irritation. It has squalane and other hydrating ingredients for those with extra dry or sensitive skin."

Normal to dry skin

"For those with normal to dry skin, I really like Avène Retrinal 0.1 Intensive Multi Corrective Cream," Dr. Mian. "This cream uses retinaldehyde, which is more potent than retinol, and is formulated with hyaluronic acid for a hydrating consistency."

Mature skin

"For more advanced skin looking for improvement with fine lines, I like Vichy's LiftActiv, as it has retinol and peptides for an added boost of collagen production," says Dr. Mian.

Oily skin

"I like La Roche-Posay Retinol B3," says Dr. Mian. "It has niacinamide, which helps with oil production and is great for acne prone skin."

Slow and steady wins the race when it comes to retinol. "Gently pat dry after cleansing at night, then apply a pea sized amount, spreading evenly over the entire face," says Dr. Mian. "Follow it with a moisturizer. Do this once a week, for about three weeks."