Hair loss can be an upsetting and worrisome experience. But with a slew of wellness brands and influencers promising the best treatment, how do you know where to turn?

You should be wary of people online advertising products that offer a quick, one-size-fits-all fix, Dr. Mansha Thacker, board-certified dermatologist at Pennsylvania's St. Luke’s University Health Network tells USA TODAY.

"The hair loss industry is a billion-dollar business that tries to sell anything and everything, often overpromising results," Thacker says. "There are social media ads, wellness influencers and trichologists all pushing different treatments, and it can get overwhelming. Treatment requires a multifactorial approach, and the ideal plan is always individualized ... no single treatment works for everyone, but the right combination can make a real difference."

Here's what medical experts want you to know about the causes of hair loss and how to treat them.

Does wearing a hat cause baldness?

Wearing a hat won't make you bald in and of itself, Thacker says.

"But if you’re wearing one that's too tight or wearing it all the time without giving your scalp some air, it could lead to friction or irritation," she adds. That irritation, which can also be caused by wearing tight braids, ponytails, hair extensions or weaves, sometimes weakens hair follicles through a condition called traction alopecia, according to the American Academy of Dermatology Association (AAD).

That doesn't mean you need to toss out your favorite baseball cap, though.

"I’d recommend sticking to hats that fit comfortably and making sure you’re letting your scalp breathe now and then," she says. "And if you're wearing hats often, just make sure to keep them clean and wash your hair regularly since a greasy scalp can lead to yeast overgrowth and dandruff."

If wearing a hat doesn't cause hair loss, what does? A number of things, dermatologists say.

"Genetics often play a big role, especially in pattern baldness," Thacker says. "But hormones can also be a major factor — things like pregnancy, menopause or thyroid issues can really impact your hair. Anemia and vitamin D deficiency are two common causes of hair loss I see in my practice. Other common causes include medical conditions like alopecia areata, scalp psoriasis, lupus, traction alopecia among others. Stress and diet can also play a role."

Can hair loss be reversed?

The answer to whether your hair loss can be reversed depends on the reason you're losing hair in the first place, Thacker says.

For conditions such as hormonal imbalances or stress-related hair thinning, there's a good chance your hair will start to grow back once the issue is addressed (or after you give birth, in the case of pregnancy). If you're experiencing pattern baldness or another genetic-related hair issue, treatments such as minoxidil or hair transplant surgery may help to re-grow hair, but not always. When other causes of hair loss lead to scarring, such as certain types of alopecia, that's often irreversible.

Hair loss is extremely common. Are vitamins the solution?

The first step, if you're experiencing any kind of hair loss, should be booking an appointment with a board-certified dermatologist, Thacker says. A biopsy and bloodwork may help in figuring out what's wrong. Many dermatologists then take a holistic approach with patients, using a combination of prescription medications, red light therapy, diet, vitamins, oils, topical medications and platelet-rich plasma (PRP) therapy, a type of regenerative medicine that uses growth factors found in blood cells to heal damaged tissue.

Hair loss can be an emotional ordeal; Thacker has seen countless patients "break out in tears" when speaking about their experiences with hair loss. But the sooner you figure out why it's happening, the sooner you and your doctor can figure out a plan.

"Hair is a part of our identity. It affects confidence, self-esteem and self-worth," she says. "It’s so frustrating when people on the internet prey on their vulnerability and try to sell stuff that doesn’t work. This makes people feel more helpless because they feel that they’re trying everything and yet not getting results. If you’re dealing with hair loss, it’s important to see a dermatologist early to figure out the cause."

USA Today