Fentanyl half-life
Fentanyl needs a deliberately narrow page: half-life is not potency, overdose risk, patch behavior, or emergency context.
Every curve begins at 100%. No dose or measured body concentration is assumed.
X-axis: elapsed time. Y-axis: modeled percentage of the relative starting point remaining. This is a mathematical visualization, not a personal concentration estimate.
What a careful reader should notice first
The chart can show parent-drug decline for the selected input, but route and formulation can dominate the real interpretation.
Source angle
Read labels and source notes for route-specific context, especially when transdermal or other formulations are involved.
Do not use it for
Do not use the curve as a safety clock, conversion tool, or risk estimate.
Best next step
Compare with morphine, oxycodone, and synthetic-opioid entries while keeping potency separate from half-life.
Fentanyl: evidence and interpretation notes
Parent drug, metabolites, and formulation
The curve is narrowed to the terminal phase described after intravenous fentanyl, about 3.65 hours. Transdermal fentanyl has a much longer apparent decline after patch removal because skin continues to release drug, so the two formulations are not blended.
For the interactive chart, HalfLifeDB starts with 3.65 hours as the representative value for Fentanyl after intravenous injection. Route, formulation, sampling, and metabolites remain attached to that label instead of being hidden inside the arithmetic.
Fentanyl illustrates why formulation matters. Injection and transdermal products have very different clinical contexts, so one half-life curve cannot describe every exposure pattern.
The 7 hour value is used as an educational curve input. Transdermal systems, redistribution, and clinical monitoring questions require product-specific interpretation outside this model.
The entry cites direct DailyMed labels for injection and patch formulations plus the compound record.
The calculator does not estimate respiratory risk, analgesia, overdose risk, or safe timing.
For Fentanyl, parent-drug decline should be read separately from analgesia, respiratory risk, metabolites, and formulation. Opioid risk is not proportional to the percentage remaining in this simplified chart.
What each source contributes
- DailyMed: Fentanyl citrate injection. This product label adds formulation-specific pharmacokinetic context and does not represent every route or product.
- DailyMed: Fentanyl transdermal patch. This product label adds formulation-specific pharmacokinetic context and does not represent every route or product.
- PubChem: Fentanyl. This identity record confirms names and compound identity and does not supply a human half-life.
For Fentanyl, the numerical model is tied most closely to DailyMed: Fentanyl citrate injection. As a product label, it adds formulation-specific pharmacokinetic context; it does not represent every route or product.
Why there is no range on the chart
This profile plots 3.65 hours for Fentanyl after intravenous injection without adding an unsourced high-low band. A single supported center is more honest than manufacturing a range from unrelated routes, populations, or formulations.
InterpretationReading the curve and its category context
Reading this curve
HalfLifeDB uses 3.6 h as a representative input for Fentanyl after intravenous injection. In the simplified model, about 1.0% remains after 24 hours and about 3% remains after five half-lives, or roughly 18.3 h.
This is a short curve. The modeled amount changes noticeably over the same day, while effects, metabolites, and safety questions can still follow a different timeline. The curve is relative: it does not estimate a person's measured concentration, effects, impairment, or time to clearance.
opioid context
Opioid pharmacokinetics can differ between parent compounds and metabolites, and timing can vary by route, formulation, and individual clearance.
- Half-life is not a measure of respiratory risk or functional impairment.
- Active metabolites can matter even when the parent compound declines.
- Extended-release products require separate source context.
ComparisonTimeline checkpoints and nearby profiles
Fentanyl timeline checkpoints
| Elapsed time | Modeled remaining | Reading note |
|---|---|---|
| 6 h | 32.0% | Long-tail portion of the model |
| 12 h | 10.2% | Long-tail portion of the model |
| 24 h | 1.05% | Low modeled remainder, not a clearance guarantee |
| 2.0 days | 0.01% | Low modeled remainder, not a clearance guarantee |
| 3.0 days | 0.00% | Low modeled remainder, not a clearance guarantee |
Nearby profiles by half-life
These entries sit near Fentanyl within the opioid group when sorted by representative half-life. That makes them curve comparisons, not statements about equal potency, effects, or risk.
- Hydrocodone (4 h)
- Oxycodone (3.5 h)
- Meperidine (3 h)
- Tapentadol (4 h)
EvidencePharmacokinetic inputs and source trail
Pharmacokinetics at a glance
| Representative half-life | 3.6 h |
|---|---|
| Modeled analyte or phase | Fentanyl after intravenous injection |
| Curve type | Normalized, first-order decline |
Selection note: The curve is narrowed to the terminal phase described after intravenous fentanyl, about 3.65 hours. Transdermal fentanyl has a much longer apparent decline after patch removal because skin continues to release drug, so the two formulations are not blended.
Sources and evidence context
A linked record is not automatically proof of the displayed value. Study, labeling, review, and compound identity sources serve different purposes; notes below identify limitations when they are known.
- Official labeling DailyMed label: Fentanyl citrate injection.Official U.S. product labeling used for formulation and labeled pharmacokinetic context; its statements apply to the described product.
- Official labeling DailyMed label: Fentanyl transdermal patch.Official U.S. product labeling used for formulation and labeled pharmacokinetic context; its statements apply to the described product.
- Identity record PubChem Compound Summary: Fentanyl.Compound identity and naming record. It supplies chemistry context, not independent numerical support for the model.
BoundariesWhat this page cannot answer and where to continue
What this page does not answer
- It does not estimate impairment, intoxication, or fitness to drive.
- It does not predict urine, blood, saliva, or hair test results.
- It does not model repeated exposure, tolerance, withdrawal, or interactions.
- It does not replace clinician, pharmacist, toxicologist, or emergency guidance.
Continue with context
- All substance profiles
- Browse the opioid group
- Compare this curve
- Clearance and volume of distribution
- Bioavailability, route, and formulation
- Active metabolites and parent compounds
- First-order vs nonlinear kinetics
- Detection windows vs half-life
- Reading labels and source quality
Read the medical disclaimer, methodology, and research standards before using the model for comparison.