Canadian Blood Services says local hospitals have the blood they need at the moment, but that will change if it can't fill donation appointments.
Demand for O-negative blood is high, but donors of all types are invited to a donation clinic next Wednesday.
The drive is at the Ciociaro Club on North Talbot Road in Oldcastle from 2 p.m. to 7 p.m.
O-negative is considered a universal blood type, and when seconds count, that's the type healthcare workers reach for.
If you know your blood type is O-negative, Canadian Blood Services asks that you book an appointment to donate on August 20. The number to call is 1-888-236-6283.