Stevens–Johnson syndrome is a severe adverse drug reaction affecting the skin and mucous membrane. The causes include Sulfonamides, Anticonvulsants, etc. A patient developed ulcerations in the lips and oral cavity with difficulty in swallowing and rashes over the back, abdomen, and genitalia following administration of injection ceftriaxone 1 g intravenous (IV) b.i.d, injection pantoprazole 40 mg IV b.i.d, tablet aceclofenac + paracetamol 325 mg b.i.d, tablet cetirizine 10 mg b.i.d, chlorhexidine mouth wash, and injection metronidazole 500 mg IV t.i.d for the treatment of traumatic facial injury after 4 days of treatment. Injection ceftriaxone and tablet aceclofenac + paracetamol were suspected as the cause of this reaction. The two drugs were stopped. The patient was treated with corticosteroids, other antimicrobials, and oral topical anesthetics. Health-care providers should be careful about the possible adverse drug reactions even to commonly used drugs.