OverviewDosageSide EffectsInteractionsHalf-Life

Ranitidine (Zantac) was the 48th most commonly prescribed drug in the United States in 2017. In that year alone, there were over 16 million prescriptions. Considering how popular this drug is right now, it pays to know a little bit more about this medication, including how long ranitidine stays in your system.

The FDA states the following information regarding ranitidine half-life:

Mean effective half-life: 2.5 to 3 hours

Time to steady-state: N/A

Mean accumulation ratio: N/A

Terminal phase half-life: 2.5 to 3 hours

Ranitidine has an oral bioavailability of 50 to 60 percent. Ranitidine can accumulate so that dosage adjustment might be necessary at some point. 


What is the half-life of ranitidine?

The half-life of ranitidine is anywhere from 2.5 to 3 hours.

How long does ranitidine stay in your system?

Ranitidine is detectable in your system for the following time frames:

  • Your blood for NA.
  • Your saliva for NA.
  • Your urine for 24 hours.
  • Your hair for NA.

Based on the short half-life of ranitidine, up to three hours, it is likely this drug may leave the system within 24 hours. However, accumulation can occur.

Is it safe to take 300 mg of ranitidine daily?

Anyone taking this drug should follow the dosage information on the label or the recommendations by a physician. This medication does come in 300 mg capsules, though, so it should be safe with a doctor’s approval. Patients should not exceed that amount in a 24 hour period, though.

Is it OK to stop taking ranitidine?

Patients should continue to take this medication until advised by a healthcare professional to stop. Abruptly stopping will mean the return of high levels of stomach acid. Sometimes the medication is an as needed medication. If “as needed” a patient may stop taking it and only take it when you need it. Always listen to your physician’s instructions precisely.

Disclaimer: this article does not constitute or replace medical advice. If you have an emergency or a serious medical question, please contact a medical professional or call 911 immediately. To see our full medical disclaimer, visit our Terms of Use page.

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