Rapamycin -- originally developed as an immunosuppressant for organ transplant recipients -- has become one of the most discussed drugs in the longevity community. Off-label use of low-dose, intermittent rapamycin (sirolimus) is growing rapidly, driven by animal studies showing lifespan extension and a wave of interest from longevity physicians, researchers like Matt Kaeberlein, and self-experimenters. But rapamycin is not a supplement. It is a potent pharmaceutical that affects your immune system, lipid metabolism, blood glucose regulation, and blood cell production.
If you are taking rapamycin for longevity, blood tests are not optional -- they are the minimum safety requirement. Without regular monitoring, you have no way of knowing whether the drug is affecting your cholesterol, raising your blood sugar, suppressing your white blood cells, or stressing your liver and kidneys. The longevity community's enthusiasm for rapamycin must be matched by rigorous self-monitoring.
This guide covers the complete blood test panel recommended for rapamycin users: what to test, why each marker matters, what changes to expect, how often to monitor, and when to stop or adjust your dose.
Key Takeaways
- Rapamycin significantly raises cholesterol and triglycerides. Studies in transplant patients show mean total cholesterol increases of up to 50% and triglyceride increases of up to 95%. Even at low longevity doses, lipid monitoring is essential.
- Blood glucose and HbA1c may rise. Rapamycin inhibits mTORC2 at higher or chronic doses, which can impair insulin signalling. Fasting glucose and HbA1c should be checked at every monitoring visit.
- Full blood count is critical. Rapamycin can suppress platelet production (thrombocytopenia), lower white blood cells (leukopenia), and reduce haemoglobin (anaemia) in a dose-dependent manner.
- Liver and kidney function must be tracked. Elevated creatinine is a known side effect. Liver enzymes should be monitored as a safety baseline.
- Test at baseline, every 6-8 weeks during dose titration, then every 3 months once stable. Sirolimus trough levels help confirm your dose is in the intended range.
- At-home venous blood testing makes comprehensive monitoring accessible without a GP referral -- particularly important given that most GPs will not prescribe or monitor off-label rapamycin use.
What Is Rapamycin?
Rapamycin (generic name: sirolimus, brand name: Rapamune) is a macrolide compound originally discovered in soil bacteria on Easter Island (Rapa Nui) in the 1970s. It was developed as an immunosuppressant and has been used since 1999 in transplant medicine to prevent organ rejection. It works by inhibiting a protein called mTOR (mechanistic target of rapamycin) -- a master regulator of cell growth, metabolism, and ageing.
The longevity interest in rapamycin stems from a landmark 2009 study showing that it extended lifespan in mice by 9-14%, even when started late in life. Since then, rapamycin has consistently extended lifespan across multiple animal species -- from yeast and worms to mice and dogs. The PEARL trial (Participatory Evaluation of Aging with Rapamycin for Longevity) and other human trials are underway, but definitive evidence for lifespan extension in humans does not yet exist.
The typical longevity protocol uses intermittent, low-dose rapamycin -- usually 3-8 mg taken once weekly, rather than the daily dosing used in transplant patients (2-5 mg/day). This weekly approach is thought to preferentially inhibit mTORC1 (associated with longevity benefits) while minimising chronic mTORC2 suppression (associated with metabolic side effects like insulin resistance). However, recent research shows substantial inter-individual variability in blood levels at the same dose, making personalised monitoring essential.
Important: Rapamycin is a prescription-only medicine in the UK. It is not licensed for longevity or anti-ageing use. Off-label use should only be undertaken with medical supervision and informed consent about the limited evidence base in healthy adults. This article is for informational purposes only -- Lola Health provides blood testing services, not prescriptions.
Blood Tests for Rapamycin Users
Rapamycin affects multiple organ systems simultaneously. A comprehensive monitoring panel covers lipids, glucose metabolism, blood cells, liver function, kidney function, and -- ideally -- drug levels. Below is the complete panel with clinical rationale for each marker.
Lipid Panel
Dyslipidaemia is the most common and well-documented side effect of rapamycin. Research in transplant patients shows that sirolimus significantly increases total cholesterol, LDL cholesterol, and triglycerides. This occurs because mTOR inhibition reduces lipoprotein lipase activity and upregulates hepatic triglyceride production.
| Biomarker | Why It Matters for Rapamycin Users | What to Watch |
|---|---|---|
| Total cholesterol | Rapamycin increases total cholesterol by up to 50% in transplant studies. Even intermittent low-dose protocols can raise it meaningfully. | Increases above 6.0 mmol/L warrant clinical review. Track the trend from your baseline. |
| LDL cholesterol | LDL rises because mTOR inhibition reduces LDL receptor expression on liver cells, slowing clearance from the blood. | A rise of 20-30% from baseline is common. If LDL exceeds 4.0 mmol/L or ApoB exceeds 1.2 g/L, discuss with your prescriber. |
| HDL cholesterol | HDL may rise modestly in some users, partially offsetting LDL increases. Track the total cholesterol/HDL ratio. | Maintain above 1.0 mmol/L (men) or 1.2 mmol/L (women). A favourable TC:HDL ratio below 4.5 is reassuring. |
| Triglycerides | The most dramatic lipid change. Rapamycin downregulates Prox1 in liver cells, upregulating hepatic triglyceride production. Increases of 50-95% are documented. | Fasting triglycerides above 2.3 mmol/L are a concern. Above 5.0 mmol/L raises the risk of pancreatitis. |
| ApoB | The single best marker of atherogenic particle burden. More informative than LDL alone because it counts every artery-clogging lipoprotein particle. | Optimal is below 0.9 g/L. If rapamycin pushes ApoB above 1.2 g/L, the cardiovascular risk from the drug may outweigh the longevity benefit. |
Glucose and Metabolic Markers
Rapamycin's effect on blood glucose is dose-dependent and protocol-dependent. Long-term data from the Dutch TSC Registry shows that chronic mTOR inhibition significantly raises fasting glucose and HbA1c. However, intermittent weekly dosing -- the protocol most longevity users follow -- appears to have a smaller glucose impact than daily dosing, because it allows mTORC2 to recover between doses.
| Biomarker | Why It Matters for Rapamycin Users | What to Watch |
|---|---|---|
| HbA1c | Three-month average blood glucose. The gold standard for detecting a drift toward insulin resistance. One trial reported significant HbA1c increases in rapamycin-treated subjects. | Optimal is below 37 mmol/mol (5.5%). An increase of more than 3-4 mmol/mol from baseline, or any value above 42 mmol/mol (6.0%), warrants dose reassessment. |
| Fasting glucose | Real-time snapshot of glucose control. Rapamycin impairs insulin signalling via mTORC2 inhibition, which can raise fasting glucose. | Normal is below 5.5 mmol/L. Consistently above 6.1 mmol/L suggests the dose or frequency needs adjusting. Bryan Johnson publicly cited elevated blood glucose as a reason for discontinuing rapamycin. |
| Fasting insulin | Complements glucose by measuring the insulin required to maintain that glucose level. High insulin with normal glucose indicates early insulin resistance -- a warning sign before glucose rises. | Optimal fasting insulin is below 50 pmol/L (or below 7 mIU/L). Rising insulin is an earlier signal than rising glucose. |
Full Blood Count (FBC)
Rapamycin suppresses cell proliferation -- that is its mechanism of action. Blood cells, which are continuously produced at high rates in bone marrow, are directly affected. The Lancet Healthy Longevity systematic review confirmed that thrombocytopenia (low platelets), leukopenia (low white blood cells), and anaemia are established dose-dependent side effects.
| Biomarker | Why It Matters for Rapamycin Users | What to Watch |
|---|---|---|
| Platelets | Rapamycin reduces platelet production in a dose-dependent manner. Thrombocytopenia is one of the most common haematological side effects in transplant patients. | Normal range: 150-400 x 109/L. Below 100 x 109/L is clinically significant. Below 50 x 109/L increases bleeding risk -- stop the drug. |
| White blood cells (WBC) | mTOR inhibition suppresses immune cell proliferation. This is the mechanism that makes rapamycin useful in transplant medicine -- but for longevity users, excessive immunosuppression defeats the purpose. | Normal range: 4.0-11.0 x 109/L. Below 3.5 x 109/L warrants review. Below 2.0 x 109/L significantly increases infection risk. |
| Haemoglobin | Anaemia is a recognised side effect. Reduced red blood cell production, combined with potential iron or B12 deficiency, can lower haemoglobin. | Normal: above 130 g/L (men), above 120 g/L (women). A drop of more than 15 g/L from baseline requires investigation. |
| Neutrophils | The most abundant white blood cell type and the first line of defence against bacterial infections. Neutropenia (low neutrophils) is the most clinically relevant immune change. | Normal: 2.0-7.5 x 109/L. Below 1.5 x 109/L is neutropenia. Below 0.5 x 109/L is severe and warrants immediate cessation. |
Liver Function
Rapamycin is metabolised by the liver via the CYP3A4 enzyme system. While hepatotoxicity is not a primary concern at low doses, baseline and periodic liver monitoring is standard practice for any drug processed through this pathway. Liver enzymes also serve as a safety net -- detecting problems early before they become clinically significant.
| Biomarker | Why It Matters for Rapamycin Users | What to Watch |
|---|---|---|
| ALT | The most liver-specific enzyme. Rises when liver cells are damaged or inflamed. | Values above 3x the upper limit of normal (typically above 120 U/L) warrant pausing the drug. Mild elevations (1-2x ULN) should be rechecked at the next visit. |
| AST | Found in liver, heart, and muscle tissue. Paired with ALT to provide a fuller liver picture. | Same thresholds as ALT. The AST:ALT ratio can help distinguish liver damage from muscle damage (relevant if also exercising heavily). |
| GGT | Sensitive marker of bile duct obstruction and liver inflammation. Useful for detecting early hepatic stress. | Elevated GGT in the context of normal ALT/AST may indicate bile flow issues rather than liver cell damage. |
| Albumin | A protein made by the liver -- reflects liver synthetic function and nutritional status. The PEARL trial noted a significant decrease in plasma albumin in rapamycin-treated subjects. | Normal: 35-50 g/L. Falling albumin can indicate liver dysfunction, chronic inflammation, or nutritional deficiency. |
Kidney Function
Elevated creatinine is listed as a known side effect of sirolimus in transplant populations. While low-dose longevity protocols pose less risk, kidney monitoring ensures that any decline is detected early.
| Biomarker | Why It Matters for Rapamycin Users | What to Watch |
|---|---|---|
| Creatinine | A waste product filtered by the kidneys. Rising creatinine indicates declining filtration capacity. | Any sustained increase of more than 25% from your personal baseline warrants investigation. |
| eGFR | Estimated glomerular filtration rate -- the best single measure of kidney function. Calculated from creatinine, age, and sex. | Above 90 mL/min is normal. A drop below 60 mL/min is clinically significant. Track the trend, not a single reading. |
Sirolimus Trough Level
For transplant patients, therapeutic drug monitoring of sirolimus is standard practice. For longevity users, trough levels are not strictly required but are increasingly recommended by longevity physicians to confirm that your dose produces the intended blood level.
Sirolimus Trough Level Testing
A sirolimus trough level measures the concentration of the drug in your blood just before your next dose. For longevity users on weekly dosing, this means drawing blood immediately before your weekly dose (i.e., 7 days after your last dose).
- Transplant target range: 4-12 mcg/L (with concurrent ciclosporin) or 12-20 mcg/L (sirolimus alone)
- Longevity range: No established therapeutic range exists for off-label longevity use. Most longevity physicians aim for trough levels well below transplant ranges -- typically below 5 mcg/L, with many targeting undetectable or near-undetectable trough levels on weekly dosing.
- When to test: At least 5-7 days after initiating therapy or any dose change (to reach steady state). Then periodically to confirm consistency.
- Method: Liquid chromatography-tandem mass spectrometry (LC-MS/MS) on whole blood. Available through specialist laboratories -- not a standard NHS test.
Monitor Your Rapamycin Blood Markers From Home
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The Rapamycin Monitoring Schedule
Monitoring frequency should match your dosing phase. During initial titration, blood tests need to be more frequent. Once you are on a stable dose with consistent results, the interval can be extended.
| Timepoint | Tests Required | Purpose |
|---|---|---|
| Before starting (baseline) | Full lipid panel, HbA1c, fasting glucose, FBC, liver function (ALT, AST, GGT, albumin), kidney function (creatinine, eGFR), fasting insulin | Establish your personal reference values. Identify any pre-existing dyslipidaemia, glucose intolerance, or cytopenias that would increase risk. |
| 6-8 weeks | Full lipid panel, HbA1c, fasting glucose, FBC, liver function, kidney function. Optional: sirolimus trough level. | First safety check. Most lipid changes appear within the first 4-8 weeks. Detect any haematological suppression early. Adjust dose if needed. |
| 3 months | Full panel as above. HbA1c now reflects your full time on the drug. | HbA1c is a 3-month average, so this is the first timepoint where it fully reflects your rapamycin use. Compare all markers to baseline. |
| Every 3 months (ongoing) | Lipid panel, HbA1c, fasting glucose, FBC, liver function, kidney function | Ongoing monitoring. Can be extended to every 6 months once stable, but quarterly is prudent for the first year. |
| After any dose change | Full panel at 6-8 weeks post-change | Each dose adjustment resets the monitoring clock. Wait at least 5-7 days for steady state before drawing trough levels. |
Testing tip: Always test fasting (at least 10-12 hours). If you take rapamycin weekly, try to time your blood draw at the same point in your dosing cycle each time -- consistency makes trends more interpretable. For sirolimus trough levels, draw blood immediately before your next scheduled dose.
Common Blood Changes on Rapamycin
Not every change in your blood work means you need to stop. Some shifts are expected and manageable. The key is distinguishing between anticipated pharmacological effects and clinically concerning deterioration.
Expected Changes (Monitor but Do Not Necessarily Stop)
- Mild-to-moderate lipid increases: Total cholesterol rising 10-30% and triglycerides rising 20-50% from baseline is common at longevity doses. Many users manage this with dietary changes, exercise, or -- if needed -- a low-dose statin. Some longevity physicians prescribe rapamycin alongside a statin precisely for this reason.
- Small glucose elevation: Fasting glucose rising by 0.3-0.8 mmol/L is frequently reported. For most healthy individuals, this stays within the normal range. If it does not, dose reduction or a dosing holiday often resolves it.
- Mild platelet reduction: A drop of 10-20% in platelet count is common and usually clinically insignificant if platelets remain above 150 x 109/L.
- Mouth ulcers (aphthous stomatitis): Not a blood test finding but worth noting -- mild mouth sores are the most commonly reported side effect at longevity doses. They typically resolve with dose reduction or topical treatment.
Concerning Changes (Requires Action)
- Triglycerides above 5.0 mmol/L: Significantly elevated triglycerides increase the risk of pancreatitis. This warrants dose reduction or discontinuation.
- HbA1c above 42 mmol/mol (6.0%) or fasting glucose persistently above 6.1 mmol/L: Suggests clinically relevant insulin resistance. Consider reducing dose, increasing dosing interval, or taking a break.
- Platelets below 100 x 109/L: Clinically significant thrombocytopenia. Reduce dose and recheck in 4 weeks.
- WBC below 3.0 x 109/L or neutrophils below 1.5 x 109/L: Significant immunosuppression. Pause the drug and recheck in 4 weeks.
- Liver enzymes above 3x ULN: Pause the drug. Investigate other causes (alcohol, other medications, viral hepatitis).
- eGFR declining by more than 15 mL/min from baseline: Investigate. If sustained, discontinue.
- Recurrent infections or slow wound healing: Clinical signs of excessive immunosuppression, even if blood counts are normal. Consider dose reduction.
When to Stop or Adjust Rapamycin
The decision to stop, reduce, or pause rapamycin should be based on the totality of your blood work, not a single marker in isolation. However, certain findings are clear stop signals:
Stop Rapamycin and Seek Medical Advice If:
- Platelets below 50 x 109/L -- significant bleeding risk
- Neutrophils below 0.5 x 109/L -- severe neutropenia, high infection risk
- ALT or AST above 3x upper limit of normal -- potential liver injury
- eGFR below 60 mL/min (if previously normal) -- significant renal decline
- Triglycerides above 10 mmol/L -- acute pancreatitis risk
- HbA1c above 48 mmol/mol (6.5%) -- meets the diagnostic threshold for diabetes
- Any serious infection -- pneumonia, cellulitis, or systemic infection requiring antibiotics
For less severe changes, the standard approach is to reduce the dose by 50% or increase the dosing interval (e.g., from weekly to fortnightly) and recheck blood work in 6-8 weeks. If markers normalise, you can cautiously resume your previous protocol. If they do not, consider discontinuing.
Some longevity physicians recommend periodic "drug holidays" of 4-8 weeks every 6-12 months, allowing all blood markers to return to baseline. This also provides a useful check -- if your markers do not normalise off the drug, something else is contributing.
Getting Your Blood Tests Without a GP
One of the practical challenges of off-label rapamycin use is that most NHS GPs will not prescribe it, monitor it, or even order the relevant blood tests for an unlicensed indication. This leaves users reliant on private prescribers for the drug and private blood testing for monitoring.
Our Core Health 45 panel covers the essential rapamycin monitoring markers: full lipid panel (total cholesterol, LDL, HDL, non-HDL, triglycerides), HbA1c, fasting glucose, full blood count (platelets, WBC, haemoglobin, neutrophils), liver function (ALT, AST, GGT, albumin), and kidney function (creatinine, eGFR). For users who also want ApoB, hsCRP, fasting insulin, and a broader metabolic picture, the Peak Insights 70 covers 70 biomarkers in a single appointment.
Both tests use venous blood sampling by a professional phlebotomist at home -- the same clinical-grade method used by NHS laboratories. Results are delivered within 2 working days. No GP referral is needed.
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Monitor Your Rapamycin Protocol with Regular Blood Tests
Rapamycin affects lipids, blood glucose, liver enzymes, white blood cells, and kidney function. Whether you are on a weekly longevity dose or a higher immunosuppressive regimen, regular blood monitoring of these markers — plus sirolimus trough levels where possible — ensures you are getting the benefits without the risks.
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Frequently Asked Questions
What blood tests do I need before starting rapamycin for longevity?
At minimum, you need a full lipid panel (total cholesterol, LDL, HDL, triglycerides), HbA1c, fasting glucose, full blood count (including platelets, white blood cells, haemoglobin, and neutrophils), liver function tests (ALT, AST, GGT, albumin), and kidney function (creatinine, eGFR). Ideally, also include fasting insulin and ApoB for a more complete metabolic and cardiovascular baseline. These pre-treatment values are your reference point for all future monitoring -- without them, you cannot determine whether changes are caused by the drug.
How often should I have blood tests while taking rapamycin?
During the first three months (dose titration phase), blood tests are recommended every 6-8 weeks. Once you are on a stable dose with consistent results, testing every 3 months is standard practice. After a full year of stable monitoring, some longevity physicians extend the interval to every 6 months. However, any dose change resets the clock -- retest 6-8 weeks after any adjustment. For sirolimus trough levels, wait at least 5-7 days after a dose change before drawing blood.
Does rapamycin raise cholesterol?
Yes. Rapamycin significantly raises total cholesterol, LDL cholesterol, and triglycerides. Studies in transplant patients (on daily dosing) show total cholesterol increases of up to 50% and triglyceride increases of up to 95%. At lower longevity doses with weekly administration, the effect is typically less pronounced but still clinically meaningful. Many rapamycin users manage this with dietary changes, exercise, or concurrent statin therapy. If your ApoB rises above 1.2 g/L or triglycerides exceed 5.0 mmol/L, the cardiovascular risk may outweigh any longevity benefit.
Can rapamycin cause diabetes?
Rapamycin can impair insulin signalling by inhibiting mTORC2, leading to elevated fasting glucose and HbA1c. In transplant populations on daily dosing, approximately 2.5% of patients developed diabetes over a median follow-up of 5 years. With intermittent weekly dosing -- the protocol used for longevity -- the risk appears lower because mTORC2 has time to recover between doses. Nonetheless, glucose monitoring is essential. If your HbA1c crosses above 42 mmol/mol (6.0%) or fasting glucose stays above 6.1 mmol/L, your dose likely needs reducing.
Can rapamycin lower your immune system?
Yes -- that is its primary pharmacological action. Rapamycin suppresses immune cell proliferation, which is why it is used in transplant medicine. At longevity doses (typically 3-8 mg weekly), the degree of immunosuppression is much less than in transplant patients (2-5 mg daily). However, some users experience increased susceptibility to infections, slower wound healing, and mouth ulcers. A full blood count monitors this: if your white blood cell count drops below 3.0 x 109/L or neutrophils drop below 1.5 x 109/L, the dose should be reduced or paused.
What is a sirolimus trough level and do I need one?
A sirolimus trough level is a blood test that measures the concentration of the drug in your blood just before your next dose. For weekly longevity dosing, this means drawing blood 7 days after your last dose, immediately before taking the next one. While not strictly required for all longevity users, trough levels help confirm that your actual blood level matches your intended dose -- important given the large inter-individual variability in rapamycin absorption and metabolism. The test requires a specialist laboratory using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and is not part of standard blood panels.
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