Welcome to Just Answer and thanks for your question. Augmentin can be taken for a sinus infection, if it is a bacterial infection, and if it is caused by a bacterium that Augmentin will kill. The only way to know that is to have a culture and sensitivity test. Most sinus infections start out as viral infections and no antibiotics will work for them. Treatment is decongestant like Sudafed and antihistamines (Benadryl, Claritin or Zyrtec).