Picture this: You finally get your hands on that new skincare product everyone’s talking about. Slather it on during your skincare routine and wait for the results — and wait, and wait. That’s a common pain point when it comes to skincare: It can be hard to tell exactly when your new face serum is going to give you the glowing, even toned skin it promised. The good news? Depending on the active ingredient, you can get a pretty good estimate of when to expect results. We tapped NYC dermatologist Marisa Garshick, M.D. to help us figure it out.

Vitamin C

When you’ll see results: 4 weeks

Vitamin C is known for its ability to promote collagen production — which can take some time to become noticeable. That said, “some people may notice improvement in their skin as early as four weeks after use with vitamin C, with improvement in hyperpigmentation over two to three months,” says Garshick. Plus, it acts as a long-term investment in your skin. “Because vitamin C acts as an antioxidant, it helps to protect the skin from free radical damage, giving you continued skin benefits with long-term use,” she says. That’s a win-win.

Ceramides

When you’ll see results: 2-3 days

A key lipid in your skin barrier, ceramides only need to get as far as that — which is great for your skin. “It’s possible to notice benefits within days, as it helps to strengthen the skin barrier to help keep moisture in and keep irritants out,” says Garshick. And, like vitamin C, it can go a long way in maintaining healthy skin in the future. “With continued use as the barrier strengthens, ceramides are able to help lock moisture in and protect the skin, offering long-term benefits as well such as making the skin feel and look smoother,” she says.

Alpha Hydroxy Acids (AHA)

When you’ll see results: 1 day

Let us introduce our overnight celebrity, alpha hydroxy acids, which include glycolic and lactic acids. “For AHAs, it’s possible to see a result relatively quickly, even overnight, as eliminating the dead skin cells, reducing dullness, and leaving behind a glowing and more radiant complexion,” says Garshick. Exfoliants in general make pretty quick work of the dead layers of skin, but they also offer cumulative benefits. “After six to eight weeks of consistent use, AHAs can improve the appearance of skin tone and texture,” she says. And, after three to six months, they can lead to a boost in collagen production, improving the appearance of fine lines and wrinkles.

Layering your exfoliants and other active ingredients can take a little guesswork, but our guide can help.

Niacinamide

When you’ll see results: 4-8 weeks

While it usually takes at least eight weeks to appreciate the full effect of niacinamide, you might be able to glimpse certain benefits even earlier — think four weeks. Since niacinamide is one of those ingredients that does it all, these perks may come through on different timelines, explains Garshick. “Because it helps boost ceramide production, it can help to moisturize the skin as it helps to support the skin barrier and trap moisture in,” she says. “Additionally, it is soothing on the skin and can help to reduce inflammation and these benefits may be felt or noticed sooner.” For treating hyperpigmentation and getting a more even skin tone, on the other hand, you have to use it consistently in the long-term — so, think two to three months.

Hyaluronic Acid

When you’ll see results: ASAP

It’s all about immediate gratification with hyaluronic acid. In fact, says Garshick, “it is possible to see instant plumping from hyaluronic acid, as it helps to draw moisture into the skin.” And it also delivers hydration over time, too, which is important. That’s because your skin naturally produces hyaluronic acid, but it takes a nosedive with age — which is where a regular HA habit can help. “The long-term results include an overall boost in hydration leaving skin softer and smoother,” says Garshick. “That increased moisture leads to supple, healthy-looking skin in the long run.” (Just make sure to apply it to damp skin and seal it in with a moisturizer to max out those effects.)

Retinol

When you’ll see results: 2-3 months

Retinol is more of a slow-and-steady kind of ingredient. “In general, retinoids can take two to three months to show improvement, as it helps to regulate skin cell turnover. In doing so, it helps to prevent pores from becoming clogged,” says Garshick. The upside is that you’ll see a gradual improvement in skin tone and texture, as well as a reduction in breakouts.

Plus, retinol is another one of those ingredients where an early investment pays off in spades. “With time, because it also works to stimulate collagen production, you will also see an improvement in fine lines and wrinkles,” says Garshick. “While skin cell turnover normally occurs every 28 days, using a retinol or retinoid helps to speed up this process to keep the skin looking youthful.”

Fun fact: Salicylic acid, or BHA, and retinol can do serious magic for skin. Here’s why.

Beta Hydroxy Acids (BHA)

When you’ll see results: 8 weeks

Beta hydroxy acids, a.k.a. salicylic acid, can work quickly in the right formulation. For instance, when used as a spot treatment, “it can have some immediate anti-acne benefits, as it helps to reduce inflammation and may help to dry out a pimple,” says Garshick. But if you’re dealing with hormonal breakouts on a regular basis, for instance, you’ll need to wait a bit before you see those long-term, full-face benefits, since “unclogging the pores can take eight to 12 weeks to see improvement,” she says. In fact, she recommends using a given acne product for at least two or three months before determining whether or not it’s working for you.

The moral of the story? Good things take time — but clearly, it can be worth it.

Keep reading about the best active ingredients:

• When You’ll See Results From Your Fave Glow Recipe Products
• Retinol vs. Retinoids: What’s the Difference?
• What Is Hyaluronic Acid and Why You Need It