Police are appealing for a woman who rang the Calderdale NHS 111 number to come forward.
The woman who called herself ‘Sarah’ was said to be “in distress” when she made the call at 4.22pm on Thursday.
She claimed to have been the victim of a crime and to have taken a large amount of tablets.
Since then police in Calderdale have been trying to trace the woman, who said she was in Sowerby Bridge, to check on her welfare.
Chief Inspector Viv Cutbill, of Calderdale Police, said: “It is vital that we find ‘Sarah’ as soon as possible so we can make sure she is OK or get her any medical attention she may need. Officers are currently out looking for her but it is a very big area to search and we don’t have a great deal of information on which to go on. We need her, or anyone who knows her to come forward immediately.
“We will give ‘Sarah’ any help or advice she needs and ensure she gets any necessary medical attention but we need her to get in contact.”
Police can be reached on 101.