Introduction: Tetracyclines, such as doxycycline, are well-described in literature as a culprit for pill-induced esophagitis. Although rare, there may be a connection to gastric mucosal injury. Given the ubiquitous use of doxycycline, it is worthwhile to investigate the association. Case Description/Methods: A 61 year-old man presented with syncope, melena and acute anemia. Esophagogastroduodenoscopy (EGD) showed erosions and two clean-based ulcers (5 mm and 8 mm) in the antrum (Figure 1A and 1B). Retroflexed view of the incisura revealed fibrinous deposition on the cardia and fundus that was unable to be washed off despite irrigation and suctioning (Figure 1C). Biopsies demonstrated idiosyncratic features consistent with doxycycline-induced injury, with reactive erosions and superficial fibrinoid vascular degeneration. The patient had been taking doxycycline 100 mg daily for three years for chronic dermatomyositis. He was started on pantoprazole twice daily to facilitate mucosal healing and an alternative agent in place of doxycycline was recommended. Follow-up EGD ten weeks later showed normal gastric mucosa without evidence of prior injury. Biopsies were not obtained given healed appearance of the tissue (Figure 1D). Discussion: While doxycycline is widely recognized as an etiology of pill esophagitis, its effect on the gastric mucosa has been highlighted in very few cases. Doxycycline-induced gastric injury is described endoscopically as a superficial, erythematous mucosal erosion with occasional deep ulceration in the antrum or body. It presents with an adherent, light-colored and fibrinous plaque. Histologically, there are reactive changes in the foveolar cells with mucin loss and serrated gastric pits. There is also a distinct pattern of superficial eosinophilic capillary vascular degeneration, which is associated with superficial mucosal necrosis and scattered fibrinous microthrombi (Figure 1E). Clinically, patients present with nonspecific symptoms of epigastric pain or substernal burning. If history reveals doxycycline use, an EGD can be helpful. In most cases, once the offending agent is removed, the symptoms do resolve. It is unclear why only a small subset with doxycycline ingestion develops gastric injury, although we postulate that the incidence is likely under-recognized. It remains unknown how long-term or repeated usage affects the gastric mucosa, as patients on this medication do not routinely undergo endoscopic evaluation in the absence of overt upper gastrointestinal symptoms.Figure 1.: Endoscopic images showing diffuse necrosis of stomach.