TORONTO -- J.K. Rowling is facing backlash online after being accused of making transphobic comments on social media.

The "Harry Potter" author took to Twitter on Saturday to share an opinion article titled "Creating a More Equal Post-COVID-19 World for People Who Menstruate," calling out the article’s use of the phrase "people who menstruate."

"I'm sure there used to be a word for those people," Rowling wrote in a tweet. "Someone help me out. Wumben? Wimpund? Woomud?"

The author quickly became a trending topic on Twitter with users calling out her comments as being "anti-trans" and "transphobic" because transgender and non-binary people can also menstruate.

Survivor's first trans contestant, Zeke Smith, replied to the author writing, "Hi! I'm a man! I menstruate! Stop being an asshole!"

Actress Patti Harrison wrote on Twitter that the Rowling's choice to tweet about "trans women not being real women RIGHT NOW during BLM uproar really shows her depth of thought about trans people AND black people..."

"Rent" alum Anthony Rapp also took to Twitter to express his frustration over Rowling's comments.

"She has such a powerful voice. Why is she using that voice to die on a hill of transphobia? It is damaging and sad and makes zero sense. Is it really her belief that trans women somehow threaten her own selfhood? What is she so [expletive] afraid of?" Rapp wrote.

Despite the backlash, Rowling doubled down on her comments in a thread of follow-up tweets criticizing the idea that someone's biological sex isn’t real.

"If sex isn't real, there's no same-sex attraction. If sex isn't real, the lived reality of women globally is erased. I know and love trans people, but erasing the concept of sex removes the ability of many to meaningfully discuss their lives. It isn't hate to speak the truth," Rowling wrote.

"The idea that women like me, who've been empathetic to trans people for decades, feeling kinship because they're vulnerable in the same way as women -- ie, to male violence -- 'hate' trans people because they think sex is real and has lived consequences -- is a nonsense," she added.

LGBTQ rights organization GLAAD spoke out against Rowling's remarks. The organization tweeted that "JK Rowling continues to align herself with an ideology which willfully distorts facts about gender identity and people who are trans. In 2020, there is no excuse for targeting trans people."

GLAAD suggested that those who want to direct their "rightful anger over Rowling's latest anti-trans comments" into something positive could do so by supporting Black trans organizations.

Rowling insisted on Twitter that she "respects every trans person's right to live any way that feels authentic and comfortable to them" and took issue with being labelled a "TERF", a trans-exclusionary radical feminist.

"I'd march with you if you were discriminated against on the basis of being trans. At the same time, my life has been shaped by being female. I do not believe it’s hateful to say so," Rowling wrote.

This isn't the first time Rowling has been accused of making transphobic remarks.

The author faced widespread criticism in December from the transgender community and other activists after tweeting support for a British researcher who lost her job for stating that people cannot change their biological sex.

Rowling also came under fire from her fans in March 2018 when she liked a tweet referring to transgender women as "men in dresses." At the time, the author's reps said she had liked the tweet by accident.