Sulfadiazin natriy ko'plab gramm-musbat va gramm-manfiy bakteriyalarga antibakterial ta'sir ko'rsatadigan o'rta ta'sirli sulfanilamid antibiotikidir.Ferment ishlab chiqarmaydigan Staphylococcus aureus, Streptococcus pyogenes, Streptococcus pneumoniae, Escherichia coli, Klebsiella, Salmonella, Shigella, Neisseria gonorrhoeae, Neisseria meningitidis va Haemophilus in Haemophilusga qarshi antibakterial ta'sir ko'rsatadi.Bundan tashqari, u in vitro Chlamydia trachomatis, Nocardia asteroides, Plasmodium va Toxoplasma ga qarshi faoldir.Ushbu mahsulotning antibakterial faolligi sulfametoksazol bilan bir xil.Biroq, so'nggi yillarda ushbu mahsulotga bakterial qarshilik kuchaygan, ayniqsa Streptococcus, Neisseria va Enterobacteriaceae.