Daniel Radcliffe got ''horrendously ill'' when he drank antifreeze on the set of 'Horns'.

The 25-year-old actor was lucky to dodge death after consuming a cup of water which contained the chemical additive - which had been added to the water to ensure it wouldn't freeze - while shooting the movie in Canada, but he didn't realise the antifreeze had caused his illness until weeks afterwards.

He said: ''It is very cold in Canada and as a solution to that, because they don't want the water to freeze in the pipes in the trailers overnight, they put antifreeze in it.

''So it's all non-potable water that comes out the tap. I did not know that, so I drank a full cup of non-potable water ... so I guess like half-antifreeze or whatever it would have been.

''I didn't realise, and then I got horrendously ill and didn't know why I had become so ill, and a couple of weeks later I went to drink a glass of water in hair and makeup and they were like, 'What are you doing? Don't do that, that's crazy you can't drink that water!' ''

After realising the additive was the cause of Daniel's near-death experience, he raced back to his trailer on the set to discover it hadn't been fitted with signs telling him not to drink the water.

Speaking on chat show 'Conan', he added: ''I just had never seen the signs. I went back and checked my trailer and there weren't signs in it that said, 'Don't drink this water,' but it was just, yeah, it was an accident.''

Catch the full interview on 'Conan' on Monday (10.11.14) on truTV - Freeview channel 68, Sky channel 565 and FreeSat channel 154) at 11pm.