{"id":62363,"date":"2024-01-12T13:45:20","date_gmt":"2024-01-12T18:45:20","guid":{"rendered":"https:\/\/www.singlecare.com\/blog\/?p=62363"},"modified":"2025-07-28T15:21:02","modified_gmt":"2025-07-28T19:21:02","slug":"ondansetron-interactions","status":"publish","type":"post","link":"https:\/\/www.singlecare.com\/blog\/ondansetron-interactions\/","title":{"rendered":"Ondansetron interactions to avoid"},"content":{"rendered":"

Ondansetron<\/span>, known under the <\/span>brand name<\/span> Zofran<\/span>, is a selective 5-HT3 <\/span>receptor antagonist<\/span> that functions as an <\/span>antiemetic<\/span> to aid in the prevention of nausea and vomiting from chemotherapy or <\/span>radiation therapy<\/span>, treatment of severe and acute nausea and vomiting, and the prevention and treatment of postoperative nausea and vomiting. <\/span>Ondansetron<\/span> is available as an injection, an oral solution, an oral tablet, and an <\/span>orally-disintegrating tablet<\/span>. <\/span>Ondansetron<\/span> can interact with certain cardiac medications, some antibiotics, and medications used for depression and mood disorders. <\/span>Ondansetron<\/span> can also affect the metabolism of other medicines, exacerbating <\/span>side effects<\/span> associated with individual drugs. It\u2019s important to be aware of <\/span>ondansetron<\/span> interactions as some of them can cause <\/span>life-threatening<\/span> effects after a <\/span>single dose<\/span> that warrant immediate medical attention. You should never take ondansetron if you have a history of an allergic reaction to ondansetron or a drug in the same class.<\/span><\/p>\n

Ondansetron drug interactions<\/span><\/h2>\n

Ondansetron can interact with several categories of medications. It is important to disclose all medications you are taking when discussing the need for an ondansetron prescription with your prescriber and pharmacist. Many possible interactions can affect the absorption of ondansetron. More critically, many ondansetron interactions can increase the chance of a cardiac arrhythmia, or irregular heartbeat, which could potentially be fatal. The table below outlines some of the most significant interactions with ondansetron.<\/span><\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n\n
Drug class or group name<\/b><\/td>\nDrug name<\/b><\/td>\nInteractions\/side effects<\/b><\/td>\n<\/tr>\n
Antifungals<\/span><\/td>\n\nIncreased risk of a cardiac arrhythmia known as torsade de pointes (TdP) as well as QT interval prolongation. Diflucan (fluconazole), Nizoral (ketoconazole), and Noxafil (posaconazole) are contraindicated with ondansetron.<\/span><\/td>\n<\/tr>\n
Cardiac antiarrhythmic drugs<\/span><\/td>\n\nIncreased risk of a cardiac arrhythmia known as torsade de pointes (TdP) as well as QT interval prolongation. Multaq (dronedarone) inhibits the metabolism of ondansetron and is contraindicated.<\/span><\/td>\n<\/tr>\n
Fluoroquinolone antibiotics<\/span><\/td>\n\nIncreased risk of a cardiac arrhythmia known as torsade de pointes (TdP) as well as QT interval prolongation.<\/span><\/td>\n<\/tr>\n
Other antibiotics<\/span><\/td>\n\nIncreased risk of a cardiac arrhythmia known as torsade de pointes (TdP) as well as QT interval prolongation.<\/span><\/td>\n<\/tr>\n
Antimalarial drugs<\/span><\/td>\n\nIncreased risk of a cardiac arrhythmia known as torsade de pointes (TdP) as well as QT interval prolongation.<\/span><\/td>\n<\/tr>\n
Chemotherapy agents (cancer drug treatment)<\/span><\/td>\n\nIncreased risk of a cardiac arrhythmia known as torsade de pointes (TdP) as well as QT interval prolongation.<\/span><\/td>\n<\/tr>\n
Antipsychotics<\/span><\/td>\n\nIncreased risk of a cardiac arrhythmia known as torsade de pointes (TdP) as well as QT interval prolongation.<\/span><\/td>\n<\/tr>\n
Antidepressants<\/span><\/td>\n\nIncreased risk of a cardiac arrhythmia known as torsade de pointes (TdP) as well as QT interval prolongation. Increased risk of serotonin syndrome.<\/span><\/td>\n<\/tr>\n
Analgesics (pain medications)<\/span><\/td>\n\nIncreased risk of a cardiac arrhythmia known as torsade de pointes (TdP) as well as QT interval prolongation. Increased risk of serotonin syndrome.<\/span><\/td>\n<\/tr>\n
Other nausea agents<\/span><\/td>\n\nIncreased risk of a cardiac arrhythmia known as torsade de pointes (TdP) as well as QT interval prolongation.<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Disclaimer: This chart is not intended to be comprehensive. Check with your healthcare professional or pharmacist about a given drug you are taking when you are prescribed ondansetron.<\/span><\/i><\/p>\n\t\t

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Ondansetron<\/span> drug interactions<\/span><\/h2>\n

The most serious medications that <\/span>ondansetron<\/span> interferes with include serotonergic medications, other drugs that prolong the QT interval, and some antibiotics. Always check the package insert to see interactions and warnings for ondansetron and the class of medications you are taking. Your health care provider can provide more comprehensive information on the interactions with ondansetron.<\/span><\/p>\n

Serotonergic Agents<\/span><\/p>\n

As a <\/span>selective 5HT3 <\/span>receptor antagonist<\/span><\/a>, <\/span>Ondansetron<\/span> blocks serotonin peripherally and centrally. Therefore, combining with other medications in the 5HT3 <\/span>receptor antagonist<\/span> class will increase the potential risk of cardiac events such as torsade de pointes and QT prolongation. Increased free serotonin can also increase the risk of serotonin syndrome.\u00a0<\/span><\/p>\n

Monoamine oxidase <\/span>inhibitors<\/span><\/a>, or MAOIs, were the first class of antidepressants developed. These medications work by blocking an <\/span>enzyme<\/span>, monoamine oxidase, which removes serotonin from the brain. By inhibiting this <\/span>enzyme<\/span>, increased serotonin levels remain available to regulate, allowing feelings of focus, emotional stability, and overall happiness. When a medication that inhibits monoamine oxidase is combined with serotonergic drugs like <\/span>ondansetron<\/span>, the serotonergic effect of MAOIs can be enhanced, which could result in a serious medical condition known as <\/span>serotonin syndrome<\/span><\/a>.<\/span><\/p>\n

MAOIs include:<\/span><\/p>\n