Johnny is a 19 year old accounting student who has come to see you as he has noticed some lumps in his groins. He first noticed them six months ago whilst he was on summer holiday in America. Whilst there, he purchased an ointment from a chemist but cannot recall the name. He was advised in the chemist to have a sexual health screen which he did and was informed all tests were negative. On examination you identify six soft non-keratinised anogenital warts and refer him to the genito-urinary medicine (GUM) clinic.
Which one of the following options is not recommended in the treatment of anogenital warts?