Last updated 2026-07-27
TL;DR
There is no FDA-cleared or peer-reviewed sirolimus dosage calculator for anti-aging use, because no completed human lifespan trial exists to calibrate one on. Off-label protocols (commonly 3-10 mg once weekly) come from small trials on other endpoints and physician experience, not a formula. Dosing has to be individualized and blood-monitored, not calculated from weight or age alone.
Is there an actual sirolimus dosage calculator for longevity use?
No. Search engines return plenty of pages that look like calculators, but none are validated tools backed by a peer-reviewed dosing algorithm for longevity or anti-aging use. That's because the FDA-approved dosing that does exist (for transplant rejection prophylaxis) was built from trials measuring organ rejection and graft survival, not lifespan or biological aging markers [1]. The original FDA label for Rapamune (sirolimus) sets a loading dose and maintenance dose in adult kidney transplant patients based on trough blood concentration targets, not a simple weight-in, dose-out calculation you could safely port to a healthy 50-year-old taking it once a week for longevity purposes [1]. Any calculator claiming to give you a personalized off-label longevity dose from your age, weight, or goals is extrapolating past what the data supports. What actually exists is a body of small human studies, mouse lifespan data, and clinical experience with intermittent low-dose protocols that researchers and prescribers use as a starting point, then adjust with blood work. That's a process, not a calculator. Sirolimus and rapamycin are the same molecule (rapamycin is the generic chemical name, sirolimus is the pharmaceutical name); you'll see both used interchangeably in dosing literature [2].
What doses have actually been tested in humans?
The human dosing data splits into two very different buckets: FDA-approved transplant dosing, and small exploratory trials in healthy or aging populations that were not designed to measure lifespan. For transplant use, the FDA label for Rapamune specifies a loading dose of 6 mg followed by 2 mg once daily, with dose adjusted to hit a target trough blood concentration, typically monitored by immunoassay [1]. That's daily dosing, aimed at sustained immunosuppression, and it comes with a boxed warning about increased risk of infection and malignancy [1]. For longevity-style research, the most cited human dosing data comes from a 2014 trial led by Joan Mannick and colleagues (Novartis), published in Science Translational Medicine, which tested RAD001/everolimus (a rapamycin analog, not sirolimus itself) in doses ranging from 0.5 mg to 5 mg weekly and 5 mg or 20 mg daily in adults over 65, looking at immune response to influenza vaccine as the primary endpoint, not lifespan [3]. That trial found the low weekly doses improved vaccine response without the metabolic side effects seen at higher doses, but it ran about 6 weeks and used everolimus, a related but distinct drug. There is no completed human trial that has dosed sirolimus itself specifically for lifespan extension and followed people long enough to measure a mortality or healthspan outcome. That is the central gap in the field, and it's the reason a validated dosage calculator can't exist yet. Every off-label protocol in circulation is an inference from short trials, animal data, and clinical experience, not a study result you can plug into an equation.
What does the animal lifespan data actually show about dose?
The strongest dose-response data on sirolimus and lifespan comes from mice, not humans, and it's genuinely strong: the National Institute on Aging's Interventions Testing Program (ITP) has tested rapamycin across multiple cohorts and consistently found lifespan extension. In the ITP's initial 2009 report in Nature, rapamycin encapsulated in food, started at 20 months of age (roughly equivalent to late-middle-age in mice), extended median lifespan by 9% in males and 14% in females compared to controls [4]. A later 2014 ITP paper found that starting rapamycin earlier, at 9 months, and at a higher dose extended lifespan further, and that effect sizes scaled with dose within the range tested [5]. That dose-response relationship in mice is a big part of why researchers take intermittent low-dose human protocols seriously. But translating a milligram-per-kilogram mouse dose to a human weekly milligram dose is not a straight unit conversion; mouse and human metabolism, mTOR pathway sensitivity, and drug half-life differ enough that allometric scaling formulas give a wide range, not a precise number. Nobody has published a validated human-equivalent-dose calculator for sirolimus based on the ITP data specifically, and any tool claiming to derive your longevity dose from mouse mg/kg figures is doing math the pharmacology doesn't fully support yet.
What weekly doses do off-label longevity protocols actually use?
Most physician-guided off-label protocols use once-weekly or twice-weekly dosing of 3 mg to 10 mg of sirolimus, sometimes paired with periodic blood level checks, rather than daily dosing at transplant-level doses. This range is drawn from prescriber practice patterns and small studies like the Mannick trial (which used related-drug doses of 0.5 to 5 mg weekly for everolimus), not from a completed sirolimus lifespan trial [3]. The logic behind intermittent dosing is pharmacological: sirolimus has a long half-life (roughly 57 to 63 hours in the transplant label population) [1], so weekly dosing can still maintain meaningful mTOR inhibition pulses while giving the immune system recovery time between doses, in theory reducing the chronic immunosuppression seen with daily dosing. That's a plausible mechanism, but it is a hypothesis extrapolated from PK data and animal studies, not something confirmed by a completed human outcomes trial. Because there's no dose that's been proven optimal, prescribers who work with this off-label typically start low, check blood trough levels and metabolic markers, and adjust based on the individual's tolerance and labs, not a fixed calculator output. That's the honest state of practice right now, and it's why Sirolimus Rx and blood work monitoring matters more than any starting-dose formula.
Why can't weight-based or age-based formulas work here?
A calculator needs an established dose-response relationship measured in the population you're calculating for. We don't have that for sirolimus and human lifespan or healthspan outcomes, so any formula claiming to output your personal longevity dose from age and weight is filling a gap with assumption, not data. Contrast this with the transplant indication, where the FDA label dosing is grounded in trials that measured actual clinical outcomes (organ rejection rates) against blood concentrations, letting prescribers titrate to a validated target range [1]. Off-label longevity dosing has no equivalent outcome-linked target: there's no trough level that's been shown to correlate with slower biological aging in a completed trial. Body weight matters for drug distribution, sure, but sirolimus is also metabolized through CYP3A4 and affected by drug interactions, kidney and liver function, and individual pharmacokinetic variability, all of which a simple weight-based calculator ignores [1]. This is also why the FDA label explicitly ties dose adjustment to measured blood concentrations rather than a static formula, even for the approved indication.
What are the real risks of getting the dose wrong?
The three risks that show up most in both label data and off-label reports are immunosuppression, mouth ulcers (stomatitis), and metabolic changes, and all three are dose-related. Immunosuppression is the mechanism, not a side effect in the usual sense: sirolimus inhibits mTOR, which dampens T-cell proliferation, and the FDA label carries a boxed warning about increased susceptibility to infection and risk of lymphoma and other malignancies with chronic use [1]. Intermittent weekly dosing is thought to reduce this risk relative to daily transplant-level dosing, but there's no completed long-term human study confirming that intermittent off-label protocols are actually safer over years of use. Mouth ulcers (stomatitis) are one of the most commonly reported adverse effects in sirolimus clinical trials, occurring in a meaningful proportion of transplant patients on the drug, and they show up in off-label users too, often dose-dependently, easing when the dose is lowered or the drug is paused [1]. Metabolic effects, including elevated LDL cholesterol, triglycerides, and in some cases new-onset hyperglycemia, are also documented in the FDA label's adverse reaction tables for transplant patients on chronic daily dosing [1]. Whether intermittent low-dose off-label use carries the same metabolic signal is less clear, since it hasn't been studied over years, but baseline and follow-up lipid and glucose panels are standard practice for people using it off-label. For the fuller picture on what accumulates with prolonged use, see Sirolimus Rx long term side effects.
Who should not use sirolimus at any dose?
People with active infections, significant kidney impairment, poorly controlled lipid disorders, or a history of certain cancers are generally considered poor candidates, and the drug carries specific contraindications and warnings on its FDA label that any dosing decision has to work around [1]. The label also warns against use in liver transplant and lung transplant patients specifically because of trial signals showing increased risk of hepatic artery thrombosis and bronchial anastomotic complications in those populations [1]. Pregnancy is another clear no: sirolimus is classified with reproductive risk warnings on the label, and it's not something to combine with pregnancy planning [1]. Drug interactions matter a lot here too, since sirolimus is metabolized by CYP3A4, meaning grapefruit juice, certain antifungals, and other CYP3A4-interacting drugs can meaningfully change blood levels even at a fixed dose. This is exactly the kind of individual variability a generic calculator can't account for. A full contraindications breakdown is worth reading before assuming any dose is safe for you: Sirolimus Rx contraindications.
How do prescribers actually decide a starting dose, if not with a calculator?
In practice, a provider-guided off-label protocol starts with a conservative dose (often in the 3 to 6 mg once-weekly range), a baseline set of labs, and a follow-up blood draw a few weeks later to check trough sirolimus levels alongside lipid panel, fasting glucose, complete blood count, and kidney function markers. That first round of labs is the real dosing tool: if trough levels come back higher than expected, or lipids spike, or white count drops, the dose gets adjusted down. If someone tolerates it well and labs stay in normal range, some protocols will consider a modest increase. This iterative approach mirrors how the FDA label itself directs transplant dosing, adjust to trough concentration and clinical response, just applied more conservatively and infrequently for the off-label longevity use case [1]. This is also why credible longevity clinics and prescribers describe this as clinical judgment plus monitoring, not a formula. If you see a website offering a free instant calculator that spits out your ideal weekly mg with no blood work involved, that's a red flag, not a shortcut.
How does off-label dosing differ from the FDA-approved transplant dose?
| Frequency | Daily [1] | Weekly or twice-weekly (practice pattern, not FDA-set) | |
|---|---|---|---|
| Typical dose | Loading 6 mg, then 2 mg/day, adjusted to trough [1] | Often 3-10 mg/week (varies by prescriber) | |
| Monitoring target | Validated trough range tied to rejection outcomes [1] | General safety labs (lipids, glucose, CBC, trough level) | |
| Outcome evidence | Transplant rejection/graft survival trials [1] | No completed human lifespan trial | |
| Boxed warning | Yes, infection and malignancy risk [1] | Same drug, same theoretical risk, less long-term data | The molecule is identical either way, sirolimus is rapamycin [2], but the goal, monitoring, and evidence base behind the number on the label are not. |
The differences are structural, more than a matter of degree: transplant dosing is daily, aimed at continuous immunosuppression, monitored against a validated trough target tied to rejection outcomes; off-label longevity dosing is typically weekly or twice-weekly, aimed at intermittent mTOR inhibition, and monitored against general safety labs rather than an outcome-validated target. | Feature | FDA-approved transplant dosing | Common off-label longevity protocols |
What should you actually do instead of trusting an online calculator?
Get blood work before you start, work with a prescriber who will check trough levels and metabolic markers on a schedule, and treat any starting dose as a hypothesis to be corrected by your labs, not a fixed number. A reasonable process looks like this: baseline CBC, full metabolic panel, fasting lipid panel, and a conversation about your personal risk factors (infection history, cancer history, kidney function) before the first dose. Then a follow-up trough level and repeat labs 4 to 8 weeks in, adjusting from there. This is slower and less satisfying than typing your weight into a box, but it's the only approach grounded in how the FDA-approved dosing framework itself works, adjust to measured response, not a static formula [1]. Sirolimus Rx connects people through this process with provider-reviewed evaluation and a fulfilling pharmacy partner, rather than offering a generic calculator output; the point is that a licensed prescriber reviews your labs and history before any dose is set, which is the part a calculator can never actually do. If you want the underlying research first, Sirolimus Rx results what the research shows and Sirolimus Rx before and after claims are good next reads, and Sirolimus Rx purity and testing covers sourcing quality once you're evaluating a specific product.
Frequently asked questions
Is there a reliable sirolimus dosage calculator online?
No. No peer-reviewed or FDA-recognized calculator exists for off-label longevity dosing of sirolimus, because no completed human lifespan trial has established a validated dose-response relationship to build one on. Tools claiming to output a personalized dose from age or weight alone are extrapolating past the evidence, not using an established formula.
What is a typical off-label sirolimus dose for longevity?
Common off-label protocols use 3 mg to 10 mg once weekly, sometimes split twice weekly, based on prescriber practice patterns and small trials of related drugs like everolimus at 0.5-5 mg weekly. These figures come from clinical experience and short trials, not a completed sirolimus lifespan study, and doses are typically adjusted using blood work rather than fixed at the outset.
Is sirolimus the same as rapamycin?
Yes. Rapamycin is the generic chemical name for the compound; sirolimus is the pharmaceutical name used on FDA labeling and prescriptions (brand name Rapamune). They refer to the identical molecule, and the terms are used interchangeably throughout the research literature.
What is the FDA-approved sirolimus dose for transplant patients?
The FDA label for Rapamune specifies a loading dose of 6 mg followed by 2 mg daily in adult kidney transplant patients, with the maintenance dose adjusted to hit a target trough blood concentration measured by immunoassay. This dosing is for transplant rejection prevention, not longevity use, and carries a boxed warning about infection and malignancy risk.
Has sirolimus been proven to extend human lifespan?
No completed human trial has measured sirolimus's effect on human lifespan. The strongest lifespan evidence is in mice, from the NIA Interventions Testing Program, which found rapamycin extended median lifespan by roughly 9-14% depending on sex and start age. Human longevity use of sirolimus remains entirely off-label and unproven for lifespan extension specifically.
How does dosing frequency differ between transplant use and longevity use?
Transplant dosing is daily, aimed at continuous immunosuppression to prevent organ rejection. Off-label longevity protocols are typically weekly or twice-weekly, based on the idea that intermittent dosing preserves some mTOR inhibition benefit while allowing immune recovery between doses. This intermittent approach is a hypothesis from pharmacokinetics and small trials, not confirmed by long-term outcome studies.
What blood tests are needed before and during sirolimus dosing?
A reasonable baseline includes a complete blood count, full metabolic panel, fasting lipid panel, and kidney function markers, followed by a trough sirolimus blood level check a few weeks after starting. Prescribers use these results, not a calculator, to decide whether to adjust the dose up, down, or hold steady.
What are the most common side effects at typical off-label doses?
Mouth ulcers (stomatitis), elevated LDL cholesterol and triglycerides, and increased infection susceptibility from immunosuppression are the most commonly reported effects, all documented in FDA label adverse reaction data from daily transplant dosing. Whether intermittent weekly off-label dosing carries the same rates over years hasn't been studied directly.
Who should avoid sirolimus regardless of dose?
People with active infections, significant kidney or liver impairment, uncontrolled lipid disorders, a history of certain cancers, or who are pregnant or planning pregnancy are generally poor candidates per FDA label warnings and contraindications. Lung and liver transplant patients specifically have documented increased complication risks with this drug on-label.
Can I just scale down the mouse dose from the NIA study to figure out my dose?
No. Allometric scaling from mouse mg/kg doses to human doses isn't a simple unit conversion; species differences in metabolism, mTOR pathway sensitivity, and drug half-life mean the math gives a wide plausible range, not a precise figure. No published, validated human-equivalent-dose calculator exists based on the NIA mouse data specifically.
Does weight-based dosing make sense for sirolimus?
Weight affects drug distribution generally, but sirolimus is also processed through CYP3A4 metabolism and affected by kidney function, liver function, and drug interactions, none of which a weight-only formula captures. Even the FDA-approved dosing model adjusts to measured blood trough levels rather than relying on weight alone.
How often should the dose be reassessed once I'm on a protocol?
Most off-label protocols recommend follow-up labs and trough level checks roughly every 2-3 months initially, then less frequently once a stable, well-tolerated dose is established, though exact intervals vary by prescriber and individual risk factors. There's no fixed schedule validated by a completed longevity trial; this is clinical judgment based on your labs.
Sources
- FDA, Rapamune (sirolimus) prescribing information label, NDA 021083/021110: FDA-approved transplant dosing, boxed warning, adverse reactions, and contraindications for sirolimus
- National Cancer Institute, NCI Drug Dictionary: sirolimus: Sirolimus and rapamycin refer to the same drug/molecule
- Mannick JB et al., Science Translational Medicine (2014): Weekly low-dose mTOR inhibitor (everolimus) trial in adults over 65 testing 0.5-20mg doses on immune/vaccine response
- Harrison DE et al., Nature, NIA Interventions Testing Program (2009): Rapamycin extended median mouse lifespan by 9% in males and 14% in females when started at 20 months
- Miller RA et al., Aging Cell, NIA Interventions Testing Program (2014): Earlier or higher-dose rapamycin start further extended mouse lifespan, showing a dose-response relationship