Humberside Police has seen an increase in reports of drink spiking in a number of pubs in Beverley, Driffield, Market Weighton and Kirkella.
Inspector Robert Cocker is now warning people to take care ahead if they are heading out to pubs this weekend.
Inspector Cocker said: "There has been an increase in drink spiking reports in East Riding pubs.
"We have received complaints from pubs in Beverley, Driffield, Market Weighton and Kirkella.
The force has also released tips on how to avoid drink spiking.
Inspector Cocker said: "Some clubs give out drink stoppers for the top of your bottle to prevent someone dropping something in your drink.
"There are also testing kits with strips that detect certain drugs but these do not test for all types of drugs and often do not work.
"Drink spiking can happen in any situation. However, there are a few things you can do to protect yourself."
Dr Sarah Jarvis from DrinkAware has also offered advice.
She said: "Get into the habit of never leaving your drink unattended and don’t accept a drink from someone you don’t know.
"Keep an eye on your drink at all times – don’t go off and dance then come back and drink the rest.
"Avoid drinking too much alcohol by sticking to the UK Chief Medical Officers' (CMO) low risk drinking guidelines of 14 units a week for both men and women. This will put you in the best position to be alert to anything suspicious and able to look out for your friends."