Containers for warmth in bed were in use as early as the 16th century. The earliest versions contained hot coals from the dying embers of the fire, and these bed warmers were used to warm the bed before getting into it.

Containers using hot water were soon also used, with the advantages that they could remain in the bed with the sleeper and were not so hot as to be a fire risk.

Prior to the invention of rubber that could withstand sufficient heat, these early hot-water bottles were made of a variety of materials, such as zinc, copper,[1] brass,[2] glass,[3] earthenware[4][3][5] or wood. To prevent burning, the metal hot water flasks were wrapped in a soft cloth bag.