Does Ondansetron Interact With Tramadol?

Name: Does Ondansetron Interact With Tramadol?
Creator: OmniRx Health

7.3 Tramadol Although no pharmacokinetic drug interaction between ondansetron and tramadol has been observed, data from 2 small trials indicate that when used together, ondansetron may increase patient-controlled administration of tramadol.

Reviewed by the OmniRx Health clinical team•Last reviewed Jul 4, 2026

Severity: Moderate

Severity basis: drug interactions section (keywords: may increase). Combining Ondansetron (5-HT3 antiemetic) and Tramadol (Opioid analgesic) is classified as a moderate interaction.

What to Do

Use this combination with caution. Your prescriber may monitor you more closely or adjust doses.

How This Interaction Works

Interactions like this one can happen when two medicines have overlapping effects, or when one changes how the other is absorbed, broken down, or cleared from the body. Ondansetron is a 5-ht3 antiemetic and Tramadol is a opioid analgesic; together they are documented as a moderate interaction. How much this matters depends on your dose, your other medications, and your overall health.

If You Take Both Medications

If you have been prescribed both Ondansetron and Tramadol, do not start, stop, or change either medication on your own — some medicines are unsafe to stop suddenly. Tell your prescriber and pharmacist that you take both so they can decide whether the combination is right for you, adjust the dose, monitor you more closely, or suggest an alternative.

From the FDA Label

7.3 Tramadol Although no pharmacokinetic drug interaction between ondansetron and tramadol has been observed, data from 2 small trials indicate that when used together, ondansetron may increase patient-controlled administration of tramadol.

Source: FDA structured product labeling (set_id 00327696-c496-4c83-a63e-9e29fd6246d4).

Ondansetron

5-HT3 antiemetic

Brands: Zofran

View Ondansetron safety profile

Tramadol

Opioid analgesic

Brands: Ultram, ConZip

View Tramadol safety profile

Check these against your full medication list in our free Interaction Checker

Frequently Asked Questions

Can you take Ondansetron and Tramadol together?

Ondansetron and Tramadol have a documented moderate interaction. Use this combination with caution. Your prescriber may monitor you more closely or adjust doses.

How serious is the Ondansetron and Tramadol interaction?

It is classified as a moderate interaction, based on the FDA label's drug interactions section (keywords: may increase). A moderate interaction can be clinically meaningful and usually calls for monitoring or a dose adjustment.

What should I do if I'm taking both Ondansetron and Tramadol?

This information is educational — not medical advice.

This page is provided for general educational purposes and summarizes publicly available data from sources such as the U.S. Food & Drug Administration. It is not a substitute for the judgment of a licensed clinician and should not be used to start, stop, or change any medication. It may be incomplete or out of date, and individual circumstances vary. Always talk with your prescriber or pharmacist about your specific medications and health conditions. If you think you may have a medical emergency, call 911.

Questions About Your Medications?

A licensed OmniRx provider can review your full medication list and help you understand what's safe for you — no office visit required.

Other Ondansetron Interactions

Other Tramadol Interactions

Sources & References

Learn more about where our data comes from and how we write and review medical content.