Azithromycin and roxithromycin dosage and evidence
Written by Aaron CuhaReviewed Sep 2026
The short answer
Two approved antibiotics that cleared about 97 percent of worn-out 'zombie' human cells in one lab test, while their close cousin erythromycin did nothing.
Evidence grade for Azithromycin and roxithromycin: Moderate. The rule: at least one finished study in people, and at least 100 people who took it. The sum on this page: 1 completed trial, 480 people given it. A grade counts how much has been done to people, not whether it works.
- People given it
- 480
- Human studies
- 1
- Found nothing
- 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.
Azithromycin is FDA-approved as an antibiotic (Zithromax and generics). Roxithromycin is not sold in the United States, but is approved in the United Kingdom, Australia and many other countries. Neither is approved, or in any registered trial, for clearing worn-out cells, ageing or longevity.
No first-hand reports gathered yet. That is a gap in what we have collected, not a finding that nothing has been reported.
Goal pages: Ageing and longevity, Heart and circulation
In plain English
In plain English, from Aaron
This is how I would explain it to a friend. The evidence, with the numbers, is further down the page.
These are two common antibiotics. One lab paper found they killed worn-out 'zombie' cells in a dish. Some people now talk about taking them to slow ageing. Nobody has tested that in animals or people.
What people take it for
- Clearing zombie cells to slow ageing.
- A cheap zombie-cell drug from the pharmacy.
What studies in people showed
The zombie-cell result is one lab paper, in cells in a dish. There, it cleared about 97 percent of zombie cells. The best test of long-term use in people went badly. 480 transplant patients took a low dose three times a week, or a dummy pill, for two years. It was stopped early. At two years, 56.6 percent were alive on the drug and 70.1 percent on the dummy. A records study also linked short courses to more heart deaths.
What people report
Reports, not study results
The good
- We have not collected user reports on taking it for ageing.
The bad
- In transplant patients, two years of low-dose use came with more cancer relapses and fewer people alive.
- Short courses were linked to about 47 extra heart deaths per million courses.
- Long-term use breeds germs that resist antibiotics.
Where these come from: The bad lines come from the human studies and notes on this page. We have not collected user reports on this one yet.
My bottom line
One lab dish result does not justify years of antibiotics. The one long-term test in people went the wrong way. Keep antibiotics for infections.
An opinion, not a finding. I am a coach, not a doctor.
What it has been measured to do
Measured in people
Goals Azithromycin and roxithromycin has been tested for in people, biggest studies first. We count only what the studies on this page say, so the real numbers may be higher.
- Living longer480 people · 2 studies
- Heart attacks and strokesno headcount stated · 1 study
34 of the 36 indexed goals have no study of any kind behind Azithromycin and roxithromycin
No study in people, animals or cells on this page reports a result for these. That does not prove Azithromycin and roxithromycin does nothing for them. It does mean anything you have heard about Azithromycin and roxithromycin and one of these did not come from a study cited here.
Show full evidence
What is Azithromycin and roxithromycin?
Two approved antibiotics that cleared about 97 percent of worn-out 'zombie' human cells in one lab test, while their close cousin erythromycin did nothing. That is a single lab paper from a team with a stated business interest. And the largest study of long-term azithromycin in people was stopped early when blood cancer relapses piled up, with fewer people alive on it at two years.
The claim that these two antibiotics clear zombie cells rests on one paper. A team at the University of Salford published it in the journal Aging in 2018.
They used a lab screen to look for approved antibiotics that kill worn-out 'zombie' cells more than healthy ones. Two kinds of human support cells, called fibroblasts, were turned into zombie cells with eight days of a DNA-damaging chemical. Azithromycin and roxithromycin came out as hits. Erythromycin, their close parent drug, did nothing at all. The authors point to that as a sign of how specific the effect is. On a second kind of test, azithromycin cleared about 97 percent of zombie cells, which the authors call a nearly 25-fold drop. It also sped up sugar burning and the cell's self-cleaning, called autophagy, which is their proposed reason. The paper states that two authors own a small stake in Lunella Biotech.
That is all the zombie-cell evidence. Cells in a dish, one lab, one paper. There is no animal lifespan study, no animal health study, and no human study of either drug for this.
What there is plenty of is human safety data from using these drugs as antibiotics. For anyone thinking about long-term use, it does not reassure.
The ALLOZITHRO study gave 480 people who had a donor stem cell transplant 250 mg of azithromycin three times a week, or a dummy pill, for two years. Thirteen months in, the safety board saw an unexpected pile-up of blood cancer relapses and stopped the study. At two years, 56.6 percent were alive on azithromycin against 70.1 percent on the dummy. Blood cancer had come back in 33.5 percent against 22.3 percent. That was long-term, low-dose azithromycin in people, exactly what a zombie-cell use would mean, and more people died on it than on the dummy.
Separately, a study of Tennessee Medicaid records compared five days of azithromycin with no antibiotic. Heart deaths were 2.88 times as common, and deaths from any cause 1.85 times as common. In real numbers that is small: about 47 extra heart deaths per million courses, rising to 245 per million in the people with the highest heart risk. These antibiotics can upset the heart's rhythm by stretching out part of the heartbeat (the QT interval), which is the accepted explanation.
How does Azithromycin and roxithromycin work?
Both drugs are antibiotics that stop bacteria making proteins. That is what they are licensed for. The zombie-cell idea has nothing to do with that. In the Salford screen, azithromycin strongly sped up sugar burning and self-cleaning in human fibroblasts. Its effect on how the cells used oxygen went both ways: it lowered it at one dose and raised it at a higher one. The authors think these changes explain why zombie cells died more than healthy ones. Erythromycin is built almost the same way and did nothing. That is either a sign of a very precise effect, or a sign the test is picking up something narrow. Only another lab repeating it can tell which.
What have studies in people found about Azithromycin and roxithromycin?
No person has been given either drug to clear zombie cells in a study. The human data come from use as antibiotics, and the long-term data do not look good.
- ALLOZITHRO, 480 people given two years of low-dose azithromycin or a dummy pill, was stopped early by its safety board. At two years, 56.6 percent were alive on azithromycin against 70.1 percent on the dummy.
- In that study, blood cancer came back in 33.5 percent on azithromycin within two years, against 22.3 percent on the dummy.
- A records study linked short courses of azithromycin to 2.88 times the risk of heart death compared with no antibiotic. That works out to about 47 extra heart deaths per million courses.
- Long-term use of this antibiotic family is known to breed resistant germs across the population. That is why it is kept for specific conditions such as cystic fibrosis and bronchiectasis, a lung airway disease.
- No study of azithromycin or roxithromycin for zombie cells, ageing, frailty or healthy lifespan is registered anywhere.
What this does not tell you: The ALLOZITHRO patients had very weak immune systems after a stem cell transplant, so their extra deaths cannot be applied straight to a healthy person. But it is the only proper test of the long-term, low-dose use a zombie-cell plan would need, and it went badly enough to be stopped. The heart study only watched records, and the extra risk to any one person is small. Neither was built to test the zombie-cell idea, and neither can tell you whether any zombie-cell effect happens in a living person at all.
The state of the research
One lab paper is being carried a long way here.
The result is clean and hangs together. It was checked on two kinds of test, with a well-chosen comparison drug in erythromycin. But no other lab has repeated it, it has never been tested in an animal, and the lab that produced it states a business interest in the area. That is not an accusation. It is in the paper, and it is the kind of context you deserve before deciding what one lab screen is worth.
This gets a full page, not a line, because the gap between the lab claim and the human record teaches something. Using azithromycin for zombie cells would mean taking a long-lasting antibiotic again and again for years. That exact plan has been tested against a dummy pill in people, in ALLOZITHRO, and it was stopped early, with more people dying on the drug. Transplant patients with weak immune systems are not everyone, but it is still the closest thing to a test that exists.
There is also a cost to other people. Long-term use of these antibiotics breeds resistant germs. That is why it is kept for conditions like cystic fibrosis and bronchiectasis, where the benefit is proven. Using it on a hunch for ageing spends a shared resource for an unproven personal gain.
Senolytics are drugs meant to clear out worn-out 'zombie' cells, called senescent cells. No senolytic of any kind has yet made people better off in a proper human study against a dummy treatment. That is the most useful fact to carry into any senolytic talk. One pair, dasatinib plus quercetin, has lowered the number of zombie cells in people, measured in skin and fat samples. What has not followed is a study where people who got a senolytic walked further, broke fewer bones or lived longer than people who did not. The two studies against a dummy that tried, one in lung scarring (pulmonary fibrosis) and one on bone turnover after menopause, found no difference.
The evidence, in charts
Fig. 1a · how many people
480people, across 1 study in people cited here
| Study | People | Share |
|---|---|---|
| JAMA 2017 | 480 | 100% |
The whole total is one study of 480. Counts are the number of people each study on this page says it signed up. That includes studies that only watched people and gave nobody the compound. 1 more study in people gives no headcount and is not counted here. Studies still signing people up are left out, and only studies cited on this page are counted.
Fig. 1b · evidence mix
2 of 3 sources here are studies in people. The rest is not.
- Study in people · done in people267%
- Lab (cells in a dish) · cells or tissue133%
Counted from the list of sources on this page. It counts only what we cite, so there may be more studies out there. A review counts once, however many studies it sums up.
Fig. 2 · evidence over time
The studies cover 3 different years, 2012 to 2018, counted from the list of sources on this page. The newest source on file is from 2018, more than five years ago. Research on it may have gone quiet.
Fig. 3 · legal status at a glance
US
Approved
UK
Approved
AU
Approved
CA
Approved
Approved in all four countries shown. This is what the law says, not a verdict on the science. See Legal status below for the full text and any notes.
Fig. 5 · what the molecule is
- Kind of compound
- Small molecule
- Molecule weight
- Azithromycin 749.0 Da; roxithromycin 837.0 Da.
- Half-life
- About 2.8 daysLong, 1 to 7 days
- Chain length
- None on file
Half-life as stated on file: About 68 hours for azithromycin, which is unusually long; roxithromycin clears considerably faster.
No amino acid sequence is on file for Azithromycin and roxithromycin, which is expected: a small molecule is not built from amino acids.
The studies we cite
- Study in people2017Effect of Azithromycin on Airflow Decline-Free Survival After Allogeneic Hematopoietic Stem Cell Transplant: The ALLOZITHRO Randomized Clinical Trial
This trial was stopped early because the antibiotic was harming people. 480 people who had received a donor stem cell transplant took low dose azithromycin three times a week or a dummy pill for two years. The safety board halted it when cancer relapses piled up in the antibiotic group. Two years in, more of that group had relapsed and fewer were alive. Lung function was no better either. Long term low dose azithromycin did worse than nothing.
480 patients randomised to 250 mg azithromycin three times weekly or placebo for two years after allogeneic transplant. Stopped early in December 2016 after the safety board detected an imbalance in haematological relapses. Two-year airflow decline-free survival 32.8 percent on azithromycin against 41.3 percent on placebo (hazard ratio 1.3). Two-year survival 56.6 percent against 70.1 percent (hazard ratio 1.5, 95 percent CI 1.1 to 2.0). Two-year cumulative haematological relapse 33.5 percent against 22.3 percent. Long-term low-dose azithromycin produced worse outcomes than placebo.
- Study in people2012Azithromycin and the risk of cardiovascular death
Five days of azithromycin was linked to more heart deaths, though the extra risk to any one person is small. Researchers combed Tennessee Medicaid records and compared people taking the antibiotic against people taking no antibiotic. Death from heart causes was roughly three times as common during the five days of treatment. Amoxicillin showed no such rise. In real counts that is about 47 extra heart deaths for every million courses. Nobody was given anything here. Researchers only watched records.
Tennessee Medicaid cohort. During five days of azithromycin, compared with no antibiotics, risk of cardiovascular death rose (hazard ratio 2.88, 95 percent CI 1.79 to 4.63) and of death from any cause (1.85, 1.25 to 2.75). Amoxicillin showed no such increase. Estimated 47 additional cardiovascular deaths per million courses, and 245 per million in the highest cardiovascular risk decile. An observational cohort, not a randomised trial, and the absolute risk is small.
- Lab (cells in a dish)2018Azithromycin and Roxithromycin define a new family of "senolytic" drugs that target senescent human fibroblasts
In a dish only. Two kinds of human fibroblasts were turned into zombie cells, then tested against approved antibiotics. Azithromycin and roxithromycin killed zombie cells. Erythromycin, a close cousin, did not. Azithromycin cleared about 97 percent of zombie cells. Two authors own a small stake in a related company. There is no animal or human data.
Cells in culture only. MRC-5 and BJ human fibroblasts were made senescent with BrdU, then screened against approved antibiotics. Azithromycin and roxithromycin showed senolytic activity while the closely related erythromycin showed none. On a real-time impedance assay azithromycin preferentially removed approximately 97 percent of senescent cells, a near 25-fold reduction, and strongly induced aerobic glycolysis and autophagy. Two authors disclose a minority interest in Lunella Biotech. No animal or human senolytic data are reported.
Common questions
Has Azithromycin and roxithromycin been tested in people?
Yes. 480 people given it across 1 completed trial cited here, 0 of which found nothing. Two approved antibiotics that cleared about 97 percent of worn-out 'zombie' human cells in one lab test, while their close cousin erythromycin did nothing.
What is the Azithromycin and roxithromycin dosage?
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. Azithromycin is FDA-approved as an antibiotic (Zithromax and generics). Roxithromycin is not sold in the United States, but is approved in the United Kingdom, Australia and many other countries. Neither is approved, or in any registered trial, for clearing worn-out cells, ageing or longevity.
Is Azithromycin and roxithromycin FDA-approved?
Azithromycin is FDA-approved as an antibiotic (Zithromax and generics). Roxithromycin is not sold in the United States, but is approved in the United Kingdom, Australia and many other countries. Neither is approved, or in any registered trial, for clearing worn-out cells, ageing or longevity.
Is azithromycin a senolytic?
In one lab, in human fibroblasts in a dish, it cleared about 97 percent of zombie cells. That is all the zombie-cell evidence. No animal study and no human study has tested it.
Why does erythromycin not work?
Nobody knows. The authors point to it as a sign that the effect is very specific to these two antibiotics. It is just as good a reason to want another lab to repeat it before believing the effect is real.
Is it safe to take long term?
The best evidence says be careful. In transplant patients, two years of low-dose azithromycin left 56.6 percent alive at two years, against 70.1 percent on a dummy pill, and the study was stopped early. These antibiotics can also upset the heart's rhythm, and short courses have been linked to a small real rise in heart deaths.
What about the anti-inflammatory effect in cystic fibrosis?
That effect is real, and it is why azithromycin is used long term in some lung conditions. The authors of the zombie-cell paper mention it as backing. It is not the same as evidence that it clears zombie cells in a person.
Should I take antibiotics for anti-ageing?
No. On top of the missing evidence and the safety warning signs, long-term use of these antibiotics breeds resistant germs, and everybody pays that cost.