People are being warned about a "super-strength" form of ecstasy that is being blamed for the deaths of five people.
Police are urging people in Lincolnshire to come forward if they come across the drug, known as Dr Death or PMA.
Investigations are under way into deaths and serious illnesses in Derbyshire, Merseyside and Wigan over the last month.
It has been reported the heart-shaped pills – usually purple, blue, yellow or pink – are similar to ecstasy but are much stronger and can cause fatal rises in body temperature.
Lincolnshire Police said although they had not received any reports of incidents associated with the rogue batch, it was possible for the drug to have spread into the county.
Spokesman Dick Holmes said: "It has mainly been in the west of the country, but that doesn't mean to say that some of that batch hasn't made its way into Lincolnshire.
"If anyone has any information on this or any other illegal drug being sold then we would like to hear from them.
"It concerns us because people are having their lives blighted because of illegal drugs.
"Families are losing sons, daughters, fathers and grandchildren and we're working very hard to make sure it doesn't happen, but we need the co-operation of the public."
Anyone with information should call police on 101, or call Crimstoppers anonymously on 0800 555 111.