From the FDA Drug Label
6 ADVERSE REACTIONS The following clinically significant adverse reactions are described elsewhere in the labeling: Hypersensitivity Reactions [see Warnings and Precautions (5.1)] QT Prolongation [see Warnings and Precautions (5. 2)] Serotonin Syndrome [see Warnings and Precautions (5.3)] Myocardial Ischemia [see Warnings and Precautions (5.4)] Masking of Progressive Ileus and Gastric Distension [ see Warnings and Precautions (5.5)].
The long-term side effects of Zofran (ondansetron) use include:
- QT Prolongation: a change in the heart's rhythm that can lead to serious heart problems
- Serotonin Syndrome: a potentially life-threatening condition caused by high levels of serotonin in the body
- Myocardial Ischemia: a condition where the heart muscle does not receive enough blood flow, which can lead to a heart attack
- Masking of Progressive Ileus and Gastric Distension: a condition where the drug can hide the symptoms of a bowel obstruction or stomach distension 1
From the Research
Long-term use of Zofran (ondansetron) may potentially cause several side effects, including QT interval prolongation, constipation, headaches, and liver enzyme abnormalities, though serious complications are relatively uncommon. The most concerning long-term effects include QT interval prolongation, which can lead to abnormal heart rhythms, particularly in patients with pre-existing heart conditions or those taking other medications that affect heart rhythm 2. Chronic use may also cause constipation, which can become severe and lead to complications like impaction if not properly managed. Some patients experience headaches that persist with continued use. There have been reports of serotonin syndrome when Zofran is used alongside other serotonergic medications over extended periods. Additionally, long-term users might develop tolerance, requiring higher doses for the same antiemetic effect. Liver enzyme abnormalities have been reported in some cases of prolonged use, though these are typically mild and reversible 3.
While Zofran is generally considered safe for short-term use, patients requiring extended treatment should have regular medical monitoring, including ECGs to check heart function and liver enzyme tests, especially if they have pre-existing conditions or are taking other medications. A study published in 2016 found that ondansetron was associated with improved symptoms compared to placebo for moderate symptoms of nausea and vomiting in pregnancy 2. Another study published in 2014 found that the combination of ginger and ondansetron was superior to plain ondansetron as an antiemetic regimen for postoperative nausea and vomiting 4. However, the majority of the evidence suggests that the long-term use of Zofran may cause several side effects, and patients should be closely monitored.
Some key points to consider when prescribing Zofran for long-term use include:
- Monitoring for QT interval prolongation and abnormal heart rhythms
- Managing constipation and preventing impaction
- Monitoring for headaches and other adverse effects
- Checking liver enzyme tests regularly
- Adjusting doses as needed to prevent tolerance
- Considering alternative antiemetic regimens, such as the combination of ginger and ondansetron. It is essential to weigh the benefits and risks of long-term Zofran use and to closely monitor patients for potential side effects, as recommended by the most recent and highest quality study 2.