A 14 and a 15 year old are believed to taken blue transformer tablets.
Two 16-year-old's were also taken ill.
A 28-year-old man from Tiverton was arrested on suspicion of possession with intent to supply a Class A drug.
He's since been released pending further enquiries.
Police have issued a warning about the dangers of taking drugs.
Exeter care agency rated 'inadequate' and in special measures
Bosses at Horizon Care insist change
Raw sewage spews into Plymouth suburb estate and woods
Concerns raised for public health and wildlife in Woolwell
Councillor stands under trees to stop chainsaw massacre
Emergency preservation order now in place
Three years jail for charity box thief
And he can't eat in McDonald's for eight years
Spat over whether 'inadequate' children's services are as bad as MP suggests
Exeter's Steve Race believes they are in 'last chance saloon;
