Hello I have gone through your question and understand your concern. Swelling in eye is caused to retention of fluid due to the sore on the face. Infection or injury can cause puffy eyelids and under eye bags as tissue in the area is loose when compared to the other part of face, making it more susceptible to retaining fluid. Clindamycin will not only treat the sore but also reduce the eye swelling, as fluid retention will decrease with treatment of infection. Other measures that can reduce swelling are taking Panadol or Advil and elevating the head a little while sleeping to ensure proper drainage of retained fluid. Hope your concern is answered. Thank you.