Hello My Husband Is Diagnosed With Sacroilitis And Ankylosing Spondilosys.but

Hello
my husband is diagnosed with sacroilitis and ankylosing spondilosys.but his hlab27 test is negative.his esr westrgen test 1hr is 17mm. Crp, rheumatoid factor, aso titre are negative. He is suggested with saaz-od500mg, shelcal, neurobion forte.he is also having ibs.after taking saaz he feels
relaxed.how long he has to take this medicines and what will b side effects. Suggest me right.