All expenses incurred wholly & exclusively for carrying on the professional business can be claimed as deduction. Also he can claim deduction under chapter VI-A relating to donations, medical insurance premium, 80C.
However if Tax Audit is applicable(i.e. professional receipts exceeds Rs. 15 lacs during the previous year) to the profession then make sure that the expenses on whihc TDS is applicble are paid on or before 31st March, because if the profession is following Cash System of accounting then the expenditure cannot be claimed by paying the TDS on or before due date of filing the retunr u/s 139(1) as the payments are required to be made in cash itself & no deduction can be availed on accrual basis. this also applies to all other expenses such as salaries/telephone/electricity etc.. for whihc we make provisions on 31st march in case of business whihc follow mercantile system of acoc*nting.
Also for medical professional a daily case register in Form 3C & the stock of medicines is required to be maintianed if tax audit is applicable.