Police in Northumberland are appealing for anyone who finds lost medication to contact them straight away.
Officers are also warning of the dangers of taking medication which is not prescribed to them after the loss of tablets was reported at 1.20pm on Tuesday.
The medication is thought to have been left on the X18 bus from Morpeth to Berwick.
It is in the form of a number of tablets, including Clomipramine, hormone patches, Ramipril, Finasteride and Thiamine.
Anyone who has found this medication, or may know the location of it, should return it to police.
Anyone with information is asked to contact police on 101, ext 69191.