Scottish singer/DJ Calvin Harris is reportedly allergic to rumoured girlfriend, American singer/songwriter Taylor Swift's cats.

According to Life & Style, the 31-year-old I Need Your Love singer is falling sick around the 25-year-old Shake It Off singer's cats, Meredith Grey and Olivia Benson.

"Calvin sniffles and sneezes whenever he's around them! He can't stand being in her house for long periods of time because he breaks out in hives, his eyes get watery and his nose runs," a source said.

"He was up all night blowing his nose and complaining he couldn't breathe," the insider added. "He begged her to lock the cats in another room, but she refused. They had a fight over it, and he wound up leaving early."

However, the Red hitmaker, who has a history of dating high-profile celebrities including Jake Gyllenhaal, Joe Jonas, Taylor Lautner, John Mayer, Zac Efron and Conor Kennedy, is not ready to give up her pets.

"She'd rather spend time with her kitties than with a high-maintenance guy," a source told OK! "It looks like their relationship is doomed."

Rumours that Rita Ora's former boyfriend and Swift are dating started in March, and the two were pictured shopping in Nashville, dressed similarly.

Later, the two were spotted at a Kenny Chesney concert, getting cosy in the audience.

It was previously revealed that Swift has been single since splitting up with One Direction singer Harry Styles, after the pair dated for a whirlwind two months in 2014.