The man was found in possession of blue tablets and showed evidence of having taken them.
He was found unconscious but breathing in a garden in York on the morning of Saturday 4 July.
He was taken to hospital where he currently remains.
Officers are warning drug users to be vigilant if they are in possession of blue tablets or are offered blue tablets for sale.
If you have any health concerns, please seek medical advice, in an emergency call 999.
An investigation is ongoing into the supply of the drugs including any potential link to suspected drug-related deaths in other parts of the country.