Lady Gaga has cancelled the last 10 dates of the European leg of her world tour due to "severe pain".
In a statement posted on Twitter, the pop star apologised to fans and said she was "devastated", but needed to put "myself and my well-being" first.
The Grammy award-winning singer has fibromyalgia, a long-term condition which can cause pain all over the body.
Shows in London and Manchester are among those affected., according to a BBC report Saturday.
In the statement, it said the "tough decision" had been made on Friday night with "strong support from her medical team".
Ticket holders can apply for a refund from 6 February, the statement added.
"I'm so devastated I don't know how to describe it," Lady Gaga, 31, wrote. "All I know is that if I don't do this, I am not standing by the words or meaning of my music."
The announcement comes after she started the UK leg of her tour at Birmingham Arena.