Ashley Tisdale Changed How She Cares for Her Hair After Alopecia Diagnosis: 'I Couldn't Take It for Granted' (Exclusive)

The actress and singer was diagnosed with alopecia areata in her mid-20s

For Ashley Tisdale, making changes to her haircare routine was all a part of being diagnosed with alopecia.

The actress and singer, 39, was diagnosed with alopecia areata in her mid-20s after she saw a bald spot in the front of her hairline while visiting her colorist.

Since then, Tisdale — who has partnered with Pfizer and Litfulo, an FDA-approved pill for people 12 and older with severe alopecia areata — tells PEOPLE in an exclusive interview that she has "started to be way nicer to my hair and my scalp."

"I used to play with a lot of colors and dye my hair and bleach it, and I really haven't been bright blonde since then," she continues. "I used to wear extensions and I stopped doing that as well."

"I really started just treating my hair better and basically knowing that I couldn't take it for granted," adds Tisdale. "So I treat my hair better and not stress it out so much."

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Related: Ashley Tisdale Talks Candidly About Dealing with Alopecia: 'It's Nothing to Be Ashamed of'

According to Tisdale, "the hardest part about alopecia areata is that there is really no cure. It's an autoimmune disease, so they give you this diagnosis and then you're like, 'Well, what do I do?' "

"It's kind of scary, and there's the fact that you don't know when it's going to flare up, you don't know how big it's going to be," she adds. "Everyone has a different journey with alopecia and so far, luckily for me, it's been in spots that I can hide, and most of the time, it's usually stress-induced."

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The High School Musical alum says many of her flare-ups happen when she is "pretty physically and emotionally stressed."

"If I see one of the bald spots, I'm like, 'I need to calm down ... because obviously I'm too stressed out right now,' " she adds. "I have flare-ups, like, every couple years."

Related: I Was Bullied as a Teen for Having No Hair Due to Alopecia. Now I'm a TikTok Star with My Own Wig Line (Exclusive)

Alopecia areata affects almost 7 million people in the United States and 160 million people globally, according to the National Alopecia Areata Foundation.

Tisdale says her partnership with Pfizer and Litfulo, which she does not actively take herself, was an exciting one, given that it will educate others on options after they are diagnosed with alopecia areata.

"It is nice to know that there is a treatment out there and there are options, because I felt like when I was diagnosed, I didn't know any options and I didn't know what to do about it," the Frenshe founder says.

"It is something that doesn't feel good, because, obviously, our hair is kind of everything, and when there's something like that happening, especially at young ages, it's really scary," Tisdale continues.

She adds, "But to know that you're not alone and there are options is great."