A man has been charged after he allegedly spiked a woman's drink at a hotel in Newtown in Sydney's inner west, police say.

The 28-year-old man will face court on Wednesday after he allegedly spiked the woman's cocktail with GHB, causing her to collapse at the hotel.

The woman was at a hotel in Newtown when her drink was allegedly spiked. Credit:Christopher Pearce

Police said the 27-year-old woman had gone to the hotel with friends on Friday, and was sitting at a table with the group drinking a cocktail.

Police allege that the woman left her drink unattended while she went to the bathroom and, during that time, the man sat down at the table, leaned over the woman's drink and spiked it with GHB.