The 34-year old Epworth actress is expected to take up to a month away from the musical that is now showing at the Savoy Theatre.
Theatre bosses said Sheridan will get the rest and support she needs and sent her love and support from the whole team as she recovers ‘during this difficult time’.
Sheridan has received rave reviews for her starring role, that will be filled by understudy Natasha J Barnes in her absence.
The actress has suffered some abuse from social media trolls on her twitter account in recent weeks, and she apologised to her fans for not ‘being strong enough’ to carry on at present. Her father is also known to be unwell.
Sheridan, who received an OBE last year for services to drama, said Fanny Brice was her dream role.