01 / Mechanism

What it actually does.

Rapamycin binds the intracellular immunophilin FKBP12 (FK506-binding protein 12). The rapamycin-FKBP12 complex docks onto and allosterically inhibits mTORC1 (mechanistic target of rapamycin complex 1) — a kinase complex that integrates nutrient, growth-factor, and energy signals to drive protein synthesis, ribosome biogenesis, and cell growth, while suppressing autophagy [Saxton 2017]. mTORC1 inhibition flips the cellular program toward maintenance: protein turnover slows, autophagy turns on, lipid synthesis drops.

The geroscience angle is that mTORC1 activity rises with age and is one of the most reproducible pharmacological levers for extending lifespan in mice — across multiple genetic backgrounds and in both sexes, in repeated NIA Interventions Testing Program studies. Critically, chronic high-dose rapamycin also inhibits mTORC2, which causes the insulin-resistance and glucose-intolerance side effects seen in transplant patients. Intermittent (weekly) dosing appears to spare mTORC2 in animal studies, which is why off-label longevity use almost always uses a weekly schedule [Arriola Apelo 2016].

Mannick and colleagues showed in 2014 that a 6-week course of a rapamycin analog (everolimus) in adults over 65 improved influenza vaccine response by ~20%, suggesting low-dose mTOR inhibition can rejuvenate immune function rather than simply suppress it [Mannick 2014]. For deeper context on what the human longevity trials are showing, see the long read on rapamycin in humans.

02 / Dosing

Transplant vs longevity.

Setting	Dose	Schedule	Trough target
Renal transplant (low-mod risk)	6 mg load, 2 mg/day	Daily	16–24 ng/mL year 1
Renal transplant (high risk)	15 mg load, 5 mg/day	Daily	16–24 ng/mL year 1
LAM (lymphangioleiomyomatosis)	2 mg/day, adjust	Daily	5–15 ng/mL
Off-label longevity (typical)	5–8 mg	Once weekly	Not routinely monitored
Off-label longevity (PEARL arms)	5 mg or 10 mg compounded	Once weekly × 48 wk	Not routinely monitored

Bioavailability gotcha

Compounded rapamycin is approximately 3.5× less bioavailable than the commercially manufactured tablet (Rapamune). The PEARL trial's 5 mg and 10 mg compounded weekly arms correspond to roughly 1.4 mg and 2.9 mg of Rapamune-equivalent. If you're switching between compounded and brand, the milligram number is not interchangeable.

03 / Contraindications

Who should not take this.

Active infection. Especially fungal, mycobacterial, or any indolent infection. mTOR inhibition compromises adaptive immunity even at intermittent dosing.
Recent or planned major surgery. Impaired wound healing is a known class effect — typically held 2 weeks before and 4 weeks after.
Live vaccines. Avoid during dosing periods.
Pregnancy or breastfeeding. Embryotoxic in animal studies; effective contraception required during use and for 12 weeks after.
Uncontrolled hyperlipidemia. Rapamycin commonly raises triglycerides and LDL cholesterol; baseline lipids should be controlled first.
Concurrent strong CYP3A4 inhibitors / inducers. Grapefruit juice, ketoconazole, ritonavir, rifampin — large swings in rapamycin levels.

04 / Side effects

What to expect.

Aphthous ulcers / mouth sores. The most common off-label dose-limiting effect. Usually settles after 1–2 cycles or with a dose drop.
Lipid changes. Triglycerides up ~20–40%, LDL up ~10–15% at chronic continuous dosing. Less pronounced on weekly schedules.
Glucose intolerance. Mostly a chronic-daily-dosing effect via mTORC2; weekly schedules largely avoid this in animal and PEARL data.
Mild GI upset, transient.
Peripheral edema. Reported in transplant cohorts; rare at intermittent dosing.
Pneumonitis (rare, idiosyncratic). Dry cough, dyspnea — discontinue immediately and image.
Delayed wound healing. Plan around surgical and dental procedures.

05 / Monitoring labs

Baseline and follow-up.

Baseline: CBC (complete blood count), comprehensive metabolic panel, fasting lipid panel, HbA1c, fasting glucose, urinalysis. For off-label use add hsCRP, fasting insulin.
3 months: CBC, CMP, lipids, HbA1c. Document any new oral ulcers or infections.
6 and 12 months: Repeat full panel. Consider trough rapamycin level if clinically equivocal (the off-label clinics that draw it usually target <6 ng/mL on weekly schedules).
Annually thereafter: Full panel. Reassess risk/benefit with patient.
Hold dose: Around major surgery, active infection, live vaccination, or pregnancy.

06 / Cost

Honest pricing.

Source	Form	~Monthly cost (USD)	Note
Generic sirolimus	1 mg tablets (GoodRx)	$30–$80	For 6 mg/week (1 mg × 6)
Brand Rapamune	1 mg tablets	$300+	Almost no one uses brand off-label
Compounded oral solution	503A pharmacy	$60–$180	Lower bioavailability — dose adjust
Longevity-clinic consult	Telehealth subscription	$50–$200/mo	Consult, monitoring, Rx

07 / Key references

The evidence base.

Saxton RA, Sabatini DM. mTOR Signaling in Growth, Metabolism, and Disease. Cell. 2017;168(6):960–976. [Saxton 2017]
Mannick JB et al. mTOR inhibition improves immune function in the elderly. Science Translational Medicine. 2014;6(268):268ra179. [Mannick 2014]
Arriola Apelo SI et al. Intermittent administration of rapamycin extends the life span of female C57BL/6J mice. J Gerontol A Biol Sci Med Sci. 2016;71(7):876–881. [Arriola Apelo 2016]
Konopka AR, Lamming DW et al. Influence of rapamycin on safety and healthspan metrics after one year: PEARL trial results. Aging (Albany NY). 2025. [Konopka 2025]
Harrison DE et al. Rapamycin fed late in life extends lifespan in genetically heterogeneous mice (NIA ITP). Nature. 2009;460(7253):392–395. [Harrison 2009]
Pfizer. RAPAMUNE (sirolimus) prescribing information. Revised 2017. (Half-life 62 ± 16 h; whole-blood terminal disposition 82 ± 12 h.) [Rapamune PI]
Mannick JB et al. TORC1 inhibition enhances immune function and reduces infections in the elderly. Science Translational Medicine. 2018;10(449):eaaq1564. [Mannick 2018]

About this profile

Last reviewed against evidence: 2026-05-12. This profile is editorial reference content, not sponsored. Wellness Radar does not run affiliate links on prescription drugs. Off-label rapamycin use for longevity is an active area of clinical research without an approved FDA indication — decisions belong to you and a clinician who knows your full medical history, infection risk, and surgical timeline.

Rapamycin