Not Medical Advice: A white, round pill with an imprint of "R" on one side & "153" on the other is ondansetron hydrochloride 4 mg, from the class of 5HT3 receptor antagonists. It is available by prescription only. It is commonly distributed under the brand name Zofran.
Ondansetron hydrochloride is used in treatment of nausea and vomiting (including postoperatively and as a result of chemotherapy), alcohol dependence, gastroenteritis, and other conditions.
Common side effects of ondansetron hydrochloride may include dizziness; constipation; drowsiness; headache; diarrhea; tiredness; and irritation, pain, burning, or redness at the site of injection.
Severe side effects of ondansetron hydrochloride may include fainting; severe or persistent dizziness; severe allergic reactions (hives, itching, respiratory difficulty, rash, wheezing, unusual hoarseness, chest tightness, or swelling of mouth/face/lips/throat/tongue); jaw or chest pain; sudden severe headache or vomiting; leg or arm numbness; stomach pain; seizures; numbness or tingling of skin; fever; difficulty urinating; vision loss or changes; uncontrolled muscle movements; and irregular, slow or fast heartbeat.
If you experience any of the above severe side effects or any of the common side effects are persistent, we encourage you to seek medical care from your physician as soon as possible.