Trying to reassure a paranoid tripper by constantly asking them if they still feel paranoid is really not going to be very helpful. It'll just keep them feeling edgy and anxious. If you're with a friend who's used LSD and is having a bad time you could help by being there to listen to them. Help them to talk if they want to, but without constantly questioning them. If it's possible it might be a good idea to change the environment - go for a walk, change the music.
Relaxation is the key.
Go with the flow. It is a schedule 1 drug, meaning that it is considered to have no legitimate therapeutic use. LSD is a Class A drug under the Misuse of Drugs Act 1971 . Other Class A drugs are Cocaine and Heroin . A charge of possession of a drug with intent to supply can be brought by the police.