How long does sertraline (Zoloft) stay in your system?

Sertraline has a half-life of approximately 26 hours, meaning it takes about 5–6 days to be fully cleared from your system.

How long does metformin stay in your system?

Metformin has a plasma half-life of approximately 6.2 hours and is largely cleared within 24–48 hours in people with normal kidney function.

How long does fluoxetine (Prozac) stay in your system?

Fluoxetine has an extremely long half-life of 1–4 days, and its active metabolite norfluoxetine 7–15 days. Full clearance can take 4–6 weeks after stopping.

How long does ibuprofen stay in your system?

Ibuprofen has a half-life of approximately 2 hours and is largely cleared from your system within 10–12 hours.

Medication Half-Life Calculator — Drug Clearance Timeline

Step 1 — Select a Medication *

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Selected

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Half-Life

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Full Clearance (~5×t½)

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How Long Do Medications Stay In Your System?

STEP 01

Select your medication

Choose from 200+ drugs across all major categories. Each has a pre-filled half-life from FDA prescribing information. Popular: Sertraline, Metformin, Fluoxetine.

STEP 02

Enter your dose & timing

Input how many milligrams you took and how many hours ago. Both fields are required to calculate your personal clearance curve.

STEP 03

See your drug clearance curve

The calculator applies first-order elimination kinetics — the same model used in clinical pharmacokinetics — to show exactly how much drug remains at each timepoint.

NOTE

Individual variation matters

Age, kidney/liver function, genetics (CYP450), and drug interactions all affect real-world clearance. This tool shows the population average for a healthy adult.

Drug Half-Life Calculator — Frequently Asked Questions

How long does your medication stay in your system? Answers to the most common questions about drug clearance, half-life, and how medications are eliminated from the body.

What is drug half-life?+

Drug half-life (t½) is the time it takes for the concentration of a drug in your bloodstream to decrease by 50%. Most drugs require approximately 5 half-lives to be considered fully cleared from your system (below 3% of the original dose). Multiply the half-life by 5 to get the approximate full clearance time.

How long does medication stay in your system?+

It depends entirely on the drug. Short-acting medications like ibuprofen clear in 10–20 hours. Long-acting drugs like fluoxetine (Prozac) can take 4–6 weeks. Select any drug in the calculator above to see its specific clearance timeline.

Why does clearance vary between people?+

Liver and kidney function, age, genetics (CYP450 enzyme variants), body weight, and other medications all affect how quickly your body eliminates a drug. This calculator shows the population average for a healthy adult — individual results will vary.

Is this calculator accurate for drug testing purposes?+

No. Drug tests detect metabolites using different methods with different detection windows. Cannabis, for example, can be detected in urine for weeks despite clearing the blood quickly. Do not use this calculator to predict drug test results.

How Long Does Your MedicationStay In Your System?