He glances aside at the other man in vague alarm at the suggestion of a bad reaction to the herb. Have there been reports of those sorts of things? Never mind, he isn't certain that he wants to know. Especially not just before he's gathered up the courage to experiment with alien substances.

"I expect we will find out one way or another," he replies. The sooner they get this over with the sooner they can get on their way. Speaking of which. Not that he doesn't appreciate the care in which John is taking with his work but he's taking way too much time doing something Ianto himself could have had done by now (though maybe that's just his nerves talking). He fidgets at the other man's side for a moment before holding his hand out toward the other man, unable to just stand by and watch any longer.

"Look, just. Give it here." Delicately plucking the work out of the other man's fingers before he has a chance to say otherwise, he makes sure there's enough of the herb in the paper before rolling it between his fingers. It's the nervous energy, he'll vibrate out of his skin before too much longer. At least he can do this -- even if it is only rolling a joint, he thinks a little bitterly to himself, as he hands it back to the other man. "Have you got a light or are we going to be sat here while you rub two sticks together for fire as well?"