He can declare a period of sickness for up to 14 days on his JSA claim which would mean he can be excused from attendance and Jobsearch during that period. If its more longer term than that and his GP issues a medical certificate for longer than the 14 days he can sign off JSA and make a claim for ESA (Employment Support Allowance, previously incapacity Benefit)- Contribution Based.This lasts for longer than JSA Contribution Based, when he becomes well again and if he hasn't found work he can reclaim JSA and receive the remainder of his 26 weeks Contribution Based. Hope this helps