Phentermine is an amine anorectic that acts as a sympathomimetic agent and undergoes hepatic metabolism predominantly through CYP3A4. It is commonly used as a mediation to facilitate weight loss. Side effects of phentermine can include pulmonary hypertension, valvular heart disease, palpitations, increased heart rate or blood pressure, diarrhea, and cognitive impairment. Very rarely, phentermine usage has been associated with causing ischemic colitis. The mechanism of action for ischemic colitis from phentermine is not well defined but will be discussed in this review. We present a case of a woman who used phentermine daily for weight loss and was endoscopically confirmed to have ischemic colitis after presenting with abdominal pain and bloody diarrhea.

Acute interstitial nephritis (AIN) is characterized by an inflammatory infiltrate of the interstitium of the kidney, typically causing a decline in kidney function. Drug-induced AIN (also called allergic AIN) is a type of AIN. Common drugs associated with AIN are antibiotics, non-steroidal anti-inflammatory drugs (NSAIDs), and proton pump inhibitors (PPIs). A 59-year-old male with a history of recent laparoscopic robotic sleeve gastrectomy presented to the emergency department with five weeks of progressively worsening fatigue, nausea, and lightheadedness. Postoperatively, he was prescribed omeprazole 20 mg daily for gastric ulcer prophylaxis. His other home medications were amlodipine, atorvastatin, ursodiol, and budesonide-formoterol fumarate nebulizer. His physical examination was normal. Laboratory studies revealed elevated creatinine of 4.19 mg/dL from a baseline of 0.9 mg/dL two months ago and the presence of urine eosinophils. The etiology of this elevated creatinine was unclear, prompting CT-guided left renal biopsy. The biopsy showed diffuse interstitial inflammatory infiltration with numerous lymphocytes, a large number of neutrophils, and scattered eosinophils, consistent with the allergic type of AIN. Omeprazole was discontinued and the patient received a seven-day course of prednisone. Despite treatment, permanent renal damage occurred, and the patient\'s new baseline creatinine was 2.3 mg/dL. AIN caused by PPIs should be considered in the differential diagnosis of acute kidney injury (AKI). AIN can be difficult to diagnose, presenting with nonspecific symptoms, such as oliguria, malaise, nausea, and vomiting. An accurate and timely diagnosis can help prevent and treat worsening renal failure.

Erythema multiforme (EM) is a rare and typically self-limited mucocutaneous reaction known to present secondary to various triggers, with the most common being from an infectious etiology. Medications account for a small percentage of EM cases. Here, we report a case of a 55-year-old female who presented to her primary care physician with a circular rash on the palm of her right hand, which she noticed five days after being started on atorvastatin due to right branch retinal artery occlusion. The rash was identified as case of non-photoinduced EM associated with atorvastatin use presenting solely on the palmar aspect of the patient\'s hand and resolving four days after discontinuation of the medication. Current literature only describes photoinduced cases of EM secondary to statin use making this case unique, and it provides important insights about considering alternative lipid-lowering treatment options for patients with recurrent or persistent cases.

Angioedema is a rare but known side effect of angiotensin-converting enzyme (ACE) inhibitor therapy. The most common presentations of ACE inhibitor-induced angioedema describe swellings in the oropharyngeal and periorbital regions. We describe a rare case of a 58-year-old female with a history of type 2 diabetes and hypertension taking lisinopril for the past three years and presented with recurrent episodes of abdominal pain, nausea, and vomiting around the same time she started taking the drug. Multiple computed tomography (CT) scans were performed, which showed findings consistent with edema in the proximal small bowel. Due to the recurrent nature of these episodes over the last three years, along with consistent findings of small bowel edema on imaging, lisinopril-induced angioedema was suspected. As a result, the patient was switched from lisinopril to amlodipine. During our follow-up with the patient, she reported that her symptoms had resolved following the withdrawal of lisinopril.