Methotrexate vs Mycophenolic acid
Written by Aaron CuhaReviewed Sep 2026
The short answer
Two old drugs that dampen the immune system, and patients are often moved from one to the other. Both are prescription drugs with decades of use and set rules for blood test checks. That part never shows up in any supplement comparison of immune products.
- Methotrexate people
- 5,022
- Methotrexate nulls
- 1
- Mycophenolic acid people
- 227
- Mycophenolic acid nulls
- 0
Dose
Approved medicine. No human dose established for unlabelled uses
Labeled amounts sit on the prescribing information. This page records what trials measured, not a personal dose.
FDA-approved for rheumatoid arthritis, psoriasis and several cancers. Not approved to prevent heart and blood vessel disease, or for any ageing use.
Dose
Approved medicine. No human dose established for unlabelled uses
Labeled amounts sit on the prescribing information. This page records what trials measured, not a personal dose.
FDA-approved as mycophenolate mofetil and mycophenolate sodium to stop the body rejecting a transplanted organ. It carries boxed warnings, the FDA's strongest, for harm to an unborn baby, cancer and serious infection. No ageing use.
First-hand reports are counted on each profile and never added together. This page sets two published records side by side. It does not pick a winner.
Column A
MethotrexateMethotrexate, folate antimetabolite and anti-inflammatory
The best test we have of whether calming long-term inflammation makes you live longer. In a big heart trial in people, it did not cut heart attacks or strokes. In mice, it did not extend lifespan.
Column B
Mycophenolic acidMycophenolic acid, inosine monophosphate dehydrogenase inhibitor
A transplant drug that damps down the immune system. It was tested on the idea that rapamycin might help mice live longer by damping down the immune system too. It did not extend mouse lifespan in either sex. That points to rapamycin working some other way.
Side by side, on the facts we can check
| What we compare | Methotrexate | Mycophenolic acid |
|---|---|---|
| Category | Immune | Immune |
| FDA status | FDA-approved for rheumatoid arthritis, psoriasis and several cancers. Not approved to prevent heart and blood vessel disease, or for any ageing use. | FDA-approved as mycophenolate mofetil and mycophenolate sodium to stop the body rejecting a transplanted organ. It carries boxed warnings, the FDA's strongest, for harm to an unborn baby, cancer and serious infection. No ageing use. |
| Half-life | Three to ten hours at low doses, longer at high doses and in renal impairment, which is the main determinant of its toxicity. | Roughly 16 to 18 hours for mycophenolic acid after administration as mycophenolate mofetil, with enterohepatic recirculation producing a secondary peak. |
| Molecular weight | 454.4 Da. A small molecule, not a peptide. | 320.3 Da for mycophenolic acid. A small molecule, not a peptide. |
| How it works | At high cancer doses, methotrexate blocks an enzyme (DHFR) that cells need to use folate. Without it, cells cannot copy their DNA, so fast-growing cells die. At the low weekly doses used for rheumatoid arthritis, it works a different way. It blocks another enzyme (ATIC), which lets adenosine build up, and adenosine calms inflammation. It also drains folate inside cells and affects how genes are tagged (methylation). The two dose ranges act like different drugs and should not be mixed up. | Mycophenolic acid blocks an enzyme (IMPDH) that cells need to build guanine, one of the DNA building blocks, from scratch. T and B lymphocytes rely on building it from scratch, because they are poor at recycling it. So blocking the enzyme stops them multiplying, while mostly sparing other cells. That is why it works in transplants. It is also why it makes a clean test: it damps down immunity without touching the nutrient-sensing switches rapamycin acts on. |
| Studies in people | 2 | 2 |
| Evidence | Strong: 2 completed trials, 5,022 people given it | Moderate: 2 completed trials, 227 people given it |
| Legal status, US | FDA-approved, prescription only | FDA-approved, prescription only |
Frequently asked questions
What is the difference between Methotrexate and Mycophenolic acid?
Methotrexate: The best test we have of whether calming long-term inflammation makes you live longer. In a big heart trial in people, it did not cut heart attacks or strokes. In mice, it did not extend lifespan. Mycophenolic acid: A transplant drug that damps down the immune system. It was tested on the idea that rapamycin might help mice live longer by damping down the immune system too. It did not extend mouse lifespan in either sex. That points to rapamycin working some other way.
Which has stronger research evidence, Methotrexate or Mycophenolic acid?
Each compound gets a band worked out from facts we counted, with the math shown. Methotrexate is Strong (2 completed trials, 5,022 people given it). Mycophenolic acid is Moderate (2 completed trials, 227 people given it). That counts how much has been done in people. It does not rate whether either one works, and neither one is called the winner.
Are Methotrexate and Mycophenolic acid FDA-approved?
Methotrexate: FDA-approved for rheumatoid arthritis, psoriasis and several cancers. Not approved to prevent heart and blood vessel disease, or for any ageing use.. Mycophenolic acid: FDA-approved as mycophenolate mofetil and mycophenolate sodium to stop the body rejecting a transplanted organ. It carries boxed warnings, the FDA's strongest, for harm to an unborn baby, cancer and serious infection. No ageing use..
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Reviewed Sep 2026. This page puts two published records side by side. It is for learning, and it is not medical advice. When this site shows a dose, it is the dose a trial or a clinic actually used, or what people say they did, with the source attached. None of it tells you what to take.