Cymbalta Half-life. How Long Does It Stay In The System?

Last Updated: June 10, 2020

Authored by Sharon Levy, MD, MPH

Even the users who are taking Cymbalta correctly should know how long duloxetine stay in the system. However, if one needs to pass specific drug tests, understanding Cymbalta half-life is critical. Here are the key facts about how long duloxetine stays in the system.

Cymbalta Half-Life

For people wondering how long it takes to get Cymbalta out of the system, one of the key things to know is the duloxetine half-life. This refers to how long it takes for the concentration of the drug in the system to reach 50 percent. Cymbalta half-life averages 12 hours. However, it can happen sooner or take longer to occur depending on the patient.

Knowing the half-life is important for all patients, whether they are taking Cymbalta for insomnia, depression, or something else. This is because it can determine when other medications can be taken safely. Additionally, Cymbalta is addictive in some patients, and those patients need to understand half-life as it relates to taking to high of a dose and overdosing.

How Long Does Cymbalta Stay In The System?

Knowing the duloxetine half-life is important, but it doesn’t show the big picture. How long Cymbalta stays detectable in the system is much more clear. The exact length of time depends on what is being looked at.

In Blood System

When it comes to detection in the blood, duloxetine can be seen on tests for up to five days after the last dose.

In Urinary System

In the urine, it also shows up for about five days.

In Saliva

Saliva has the shortest detection period of just two days after the last dose was taken.

In Hair

Hair, on the other hand, has the longest, with detection possible up to nine months after last use.

Factors That Determine How Long Cymbalta Stays In The System

While there are general guidelines on how long the medication remains in the system, the half-life of Cymbalta and its complete elimination will vary from patient to patient. How long duloxetine stays in your system can vary due to the following elements:

  • the presence of liver or kidney disease
  • the age of the patient
  • the ratio of fat to muscle in the patient
  • how physically active the patient is
  • the pH of the urine
  • level of renal blood flow

half life of cymbalta

How long it takes the system to eliminate the medication can also vary depending on how long the patient has taken it. For example, the duloxetine side effect of weight gain can cause the user to have a higher percentage of body fat, making it harder for the body to eliminate the medication completely. But no matter how quickly or easily the body can eliminate the medication, users must be careful to avoid Cymbalta withdrawal syndrome when stopping use.

Cymbalta Metabolism

Duloxetine is an SSRI, which means that it is metabolized similarly to other drugs in its class, but the differences are still present. The metabolism of duloxetine refers to half-life and occurs when the body chemically alters the drug so it can enact the desired effects. How long it takes for Cymbalta to work depends on how quickly the body metabolizes it.


Duloxetine is never fully absorbed by the body, with as much as 70 percent of it being eliminated from the body without use. Due to a coating on the outside of the medication, absorption does not begin until two hours after taking the medication, with it taking as long as six hours in some patients.

Protein Binding

Duloxetine is excellent at binding to plasma proteins. About 90 percent of the medication not quickly eliminated by the body will bind itself to plasma proteins. Its proteins of choice are albumin and a1 acid-glycoprotein.

Route Of Elimination

A majority of duloxetine is excreted through the urine, with about 70 percent of the drug being eliminated this way. Another 20 percent is excreted through the feces. Because so much is excreted through the urine, problems with the kidneys can have a significant impact on the elimination of the medication.

Cymbalta And Drug Testing

Standard drug tests are not designed to test for the presence of antidepressants, including Cymbalta. However, that does not mean they will not cause a positive result. Cymbalta false positive drug tests have been known to happen. They occur when the chemicals in duloxetine test as being so similar to another drug that it triggers a positive. If someone is going to be taking a drug test, they should declare any medications they are taking in advance, with the expectation that the information is kept confidential unless it needs to be disclosed. Keep in mind that any antidepressant can trigger a false positive, so weighing Cymbalta vs Zoloft just for drug testing will not help.

When To Find Help

Knowing how long Cymbalta remains in the system can be helpful for users. However, if the concern is because the patient is abusing the medication, help is required. Users can get help from the drug rehabilitation facility so they can quit Cymbalta safely. Timely drug treatment can help with severe symptoms and addiction effectively.

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Published on: May 30th, 2019

Updated on: June 10th, 2020

About Author

Sharon Levy, MD, MPH

After successful graduation from Boston University, MA, Sharon gained a Master’s degree in Public Health. Since then, Sharon devoted herself entirely to the medical niche. Sharon Levy is also a certified addiction recovery coach.


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  • Elaine A. Small
    Is an itchy scalp and itchy back one of the side affects of Cymbalta?