With so many products on the market, it can be hard to figure out which ones are actually working for you — especially if you’re balancing a complex skin-care routine and trying as many buzzy new skin-care launches as you can get your hands on. For when (and if) your skin-care products take a turn, we’ve tapped skincare.com consultant and NYC-based dermatologist Joshua Zeichner, MD, to explain what to look for, how to recognize if a product works for you and when you should alert your dermatologist. Dilemma: It’s Not Working Fast Enough! Before you write off a product entirely, make sure you’ve given it a fair shot. According to Dr. Zeichner, “It often takes several weeks of continued use to begin to see the benefits.” So don’t give up just yet! Barring any adverse reactions, he recommends regularly using a new product for six to eight weeks before removing it from your routine. Dilemma: It’s Not Working AnymoreIf a product was working for you before and you’ve hit a plateau, you’re not alone. This is a common dilemma, particularly with actives like hydroxy acids and retinols, says Dr. Zeichner. Once your skin adjusts to the formula, you may need to try a higher concentration to experience benefits. If you’re concerned about moving to the next concentration level, try using your current product in your routine more frequently to see if you notice a difference. If your favorite active has become truly ineffective, Dr. Zeichner recommends speaking to your dermatologist for an alternative. Dilemma: It Started Great, But Now I’m Burning/Itching/PeelingIt’s also possible to develop a sensitivity after a product has been working just fine. When this happens, it can be difficult to pinpoint the exact product causing the issue, so Dr. Zeichner recommends “stopping everything cold turkey and slowly adding your products back in one by one after the skin has calmed down.” According to Dr. Zeichner, if you develop redness, burning, or your skin begins to peel, then it’s likely your skin no longer tolerates a particular product and it may be time to move on. Read MoreDerm DMs: What is an Exfoliating Powder?Editors Share Their Very First Skin-Care Product — and What They Use Now6 Hydrating Skin-Care Products to Apply Over Makeup