Heroin users are being warned there may be a contaminated batch of the drug in the Blackpool area.
Police say they are currently investigating reports passed to them and are urging users to seek immediate medical attention if they start to feel unwell.
Insp Sue Swift, from Lancashire Police, said: “We have received information that there may be a batch of contaminated heroin in Blackpool.
“We are looking into this and officers are making enquiries to see whether there is any foundation in these reports but it would be remiss of us not to issue a warning to drug users to be mindful that there may be a particular batch out on the streets of Blackpool that could prove harmful.
“There is the possibility this may also extend to certain batches of crack cocaine and so the warning would apply to users of that drug too to be aware.
“There is nothing at this stage to suggest that any of these contaminated batches are circulating outside of Blackpool but our advice would be for any users to seek immediate medical attention if they notice any different symptoms or start to feel unwell.
“Lancashire Constabulary takes a proactive response into tackling the issue of drugs in the county.”
Anyone with information about illegal drug related activity is asked to contact the police on 101 or call Crimestoppers anonymously on 0800 555 111.