Hair thinning can sneak up on you (maybe you’ve noticed more and more strands plastered across your shower walls) or hit you all at once (everything is fine, and then suddenly you’re anxiously analyzing your hairline in the mirror). Regardless of how or when you notice it, know that there’s something you can do about it. Start with a dermatology appointment. Derms are experts in the field of skin, hair, and nails, and they’re highly equipped to pinpoint the exact cause of your thinning hair and map out specific solutions.

You can also incorporate expert-recommended products in your routine to support hair density. That’s where we come in. We assembled a list of the best, science-backed solutions for thinning hair with the help of two top dermatologists and a celebrity trichologist. Ahead, get the lowdown on all things hair thinning, from potential causes to re-growth timelines, product selects, and more.

What Causes Hair Thinning?