Four fire engines and 21 firefighters and officers were called to a fire at a house in Bridgwater Road, South Ruislip last night.
Part of the ground floor of a terraced house was damaged by fire.
One woman left the property before the arrival of the Brigade and was treated on scene by London Ambulance Service before being taken to hospital.
The Brigade was called at 2041 and the fire was under control at 2209. Fire crews from Ruislip, Northolt and Southall fire stations attended the scene.
The cause of the fire is under investigation by the Brigade and the Metropolitan Police Service.