Serrapeptase has one of the most ambitious sales pitches in the supplement aisle. It is said to dissolve scar tissue, clear blood clots, shrink arterial plaque, drain the sinuses, and calm inflammation, all by digesting dead tissue while leaving healthy tissue alone. For a single enzyme, that is a great deal of work.

The evidence underneath it is thin, and one part of the story is rarely told in detail. The largest placebo-controlled trials of serrapeptase were run by its original manufacturer in Japan, all three missed their main goals, and as far as we can find they never appeared in a medical journal. Shortly afterward the company withdrew the drug. This guide walks through the published trials, those unpublished ones, whether the enzyme even reaches your bloodstream, where the dramatic claims come from, and how it compares with bromelain and other systemic enzymes.

The short version

  • The published evidence is small. Six placebo-controlled trials of serrapeptase alone, the largest with 193 patients, mostly measuring swelling after surgery. The one independent multi-arm trial found no pain-relieving or anti-inflammatory effect.
  • The biggest trials failed. Takeda's three modern placebo-controlled trials enrolled 892 patients, more than all six published trials combined, and none beat placebo; as far as we can find, none appeared in a journal. Takeda withdrew the drug in Japan in 2011.
  • No human study shows it reaches your blood intact. That case rests on rat studies by its original maker at doses far above any supplement.
  • Dissolving plaque, clots, and scar tissue has no supporting human evidence. The one human scar tissue study found no effect, and in the one rat study that checked clotting, it repressed the body's clot-dissolving response.
  • Bromelain is the better-studied systemic enzyme, and its evidence is still modest.
  • Talk to a clinician first if you take blood thinners, are pregnant, or have surgery scheduled.

What serrapeptase actually is

Serrapeptase, also called serratiopeptidase, is a protein-digesting enzyme made by a Serratia bacterium that was originally isolated from the gut of the silkworm. It was approved as an anti-inflammatory drug in Japan in 1968 and is still prescribed in parts of Asia, especially India, where it is often combined with conventional painkillers. In the United States it is sold as a dietary supplement.

Two details are worth getting right, because a lot of marketing gets them wrong. First, you will often read that the silk moth uses serrapeptase to dissolve its cocoon. It does not: the moth uses its own enzyme, called cocoonase, which is a different type of protease entirely. Serrapeptase came from bacteria living in the silkworm's gut, and enzymes of the same family are, if anything, one of the ways Serratia bacteria make silkworms sick. Second, serrapeptase is a zinc-dependent metalloprotease. Some published reviews describe it as a trypsin-family enzyme, which is simply incorrect, and a useful early warning that the literature around it is not always careful.

What the published trials show

A thorough search of PubMed turns up exactly six placebo-controlled trials that tested serrapeptase on its own. None enrolled more than 193 patients, the oldest dates to 1984, and every one studied a medical condition rather than healthy people:

Read together, the pattern is modest swelling benefits after surgery in small, mostly older trials, alongside a negative independent trial and repeated failures on pain. When serrapeptase is compared directly with corticosteroids after wisdom tooth surgery, the steroid wins or ties in most trials; one study found serrapeptase better for swelling and jaw stiffness while the steroid was better for pain. The only meta-analysis of those comparisons found better mouth opening with serrapeptase but no difference in swelling, even though its own conclusion claims both.

Two kinds of evidence are often cited that should not count. Many studies from India test fixed-dose combinations of serrapeptase with an anti-inflammatory painkiller, or blends of several enzymes, and those designs cannot show what serrapeptase itself contributes. And the largest serrapeptase study of all, an 850-patient study in orthopedic patients published in 2026, was not randomized and was funded by the product's maker. On the other side of the ledger, a 2026 study of women recovering from liposuction found no measurable effect on tissue stiffness, ultrasound signs of fibrosis, pain, or hardening at a daily dose of 60,000 units. A 2013 systematic review of 24 clinical studies concluded that the evidence was of poor methodological quality and insufficient to support serrapeptase as an analgesic or a supplement.

The larger trials that failed

Some of the most informative evidence on serrapeptase comes from Takeda's own trials, reviewed at a Japanese regulatory meeting in 2011, and the details are rarely reported in English. We read the archived minutes of Japan's Ministry of Health, Labour and Welfare drug re-evaluation subcommittee, from its meeting on 19 January 2011. Here is what they record.

Takeda, which sold serrapeptase as the prescription drug Dasen, had been told to show that the drug still worked by modern standards. It ran three post-marketing, randomized, double-blind, placebo-controlled trials, each giving 10 milligrams three times a day:

That is 892 patients across three modern trials, more than the six published placebo-controlled trials put together, and all of them missed their primary goal. The results were reported to regulators in 2010 and, as far as we can find, were never published in a medical journal.

Fairness requires the other half of the record. The agency's expert advisors pointed out real problems with how the trials were run, including large differences between sites in which patients were enrolled and how the main outcomes were measured, and said the results alone could not completely rule out an effect. But continuing the approval required proving one, and the committee asked for new trials. Takeda's own explanation for the failures was a strong placebo response and patients whose symptoms were too mild. The minutes also note that the earlier trials that had succeeded gave every patient placebo during a run-in period before comparing groups, a design one committee member called improper, adding that the older positive results may simply have reflected the natural course of recovery.

Rather than run more trials, Takeda withdrew the drug from the Japanese market in 2011, and generic makers followed. Singapore's regulator then stopped classifying serrapeptase as a medicine, citing a lack of benefit over placebo, while continuing to allow it in health supplements. Serrapeptase did not disappear. It moved from the prescription shelf to the supplement aisle, where no one has to prove it works.

Does it even reach your blood?

For serrapeptase to dissolve anything outside your gut, it has to cross the intestinal wall intact and still active. No human study has shown that happens. The case rests on rat work by Takeda's own researchers, in which rats given 100 milligrams per kilogram of body weight had detectable, active enzyme in their blood within a couple of hours. Converted to a human-equivalent dose by the standard body-surface-area method, that is roughly a gram for an adult, compared with the 10 to 60 milligrams in a typical supplement.

In rat blood, an earlier study by the same Takeda research group found, the enzyme did not circulate freely. It traveled bound to a blood protein that traps proteases, keeping only about a fifth of its original activity, and in a test tube the equivalent human protein also blunted its activity. There is also a formulation problem that we cover in our guide to enteric coating and delayed release: the coating that protects serrapeptase from stomach acid opens in the small intestine, which is exactly where the pancreas releases its own protein-digesting enzymes. We found no study testing whether serrapeptase survives that encounter; the studies of coated tablets measured whether protein was released, not whether it was still active. The same absorption questions hang over nattokinase, which we examine in detail in our nattokinase review.

What the units on the label mean

Serrapeptase labels list activity in units such as SPU, SU, or IU, often in the tens of thousands. Those numbers come from a test that measures how fast a sample digests casein, a milk protein. The test responds to any protein-digesting enzyme, so a unit count does not confirm what the enzyme is, brands do not use a harmonized unit, and we found no independent testing of whether commercial products contain what their labels claim. The trials, meanwhile, dosed by weight, usually 10 milligram tablets three times a day, so a label's unit count cannot be reliably matched to a trial dose.

The claims that do not hold up

Dissolving arterial plaque, clots, and scar tissue. This is the headline claim, and there is no human evidence for it. A search of PubMed finds no human study of serrapeptase and arterial plaque at all. The idea that it digests only non-living tissue while sparing healthy tissue appears twice in a widely cited 2017 review, once without a citation and once citing only a 1983 rabbit study of how an antibiotic spreads into the lung, which does not test it, and supplement sellers credit it to the late German physician Hans Nieper, who has no published work on serrapeptase in PubMed. The 2013 systematic review describes the anti-atherosclerotic claims as anecdotal.

The clot story runs into a more pointed problem. In the one rat study that measured the body's clot-dissolving system after oral serrapeptase, the enzyme markedly repressed that response rather than boosting it. A single animal study cannot tell you what happens in people, but it is the only direct evidence there is, and it points the opposite way from the marketing.

Breaking up biofilms and boosting antibiotics. This one has genuine laboratory support: serrapeptase interferes with bacterial biofilms in the test tube and can make some antibiotics work better there. But a later study found the anti-biofilm effect did not even require the enzyme's protein-digesting activity, which undercuts the idea that it works by digestion, and the best animal result came from injecting the enzyme directly into infected rat knees rather than giving it by mouth. No randomized human trial has tested oral serrapeptase against a biofilm infection.

Sinus, lung, and joint conditions, carpal tunnel, and scar tissue. These are all medical conditions, and the evidence for each is the small set of trials above, an uncontrolled 20-patient carpal tunnel pilot that also gave patients an anti-inflammatory drug, or the negative liposuction study. None of it supports using a supplement to manage them.

How it compares with other systemic enzymes

Serrapeptase belongs to a loose category called systemic enzymes: protein-digesting enzymes taken between meals in the hope that they act throughout the body rather than just helping digestion. That distinguishes them from the digestive enzymes taken with food. Here is how the main ones stack up.

EnzymeShown to reach human blood intact?Best human evidenceOur read
SerrapeptaseNot shown in people. Rat studies by its original maker only.Six small placebo trials, mostly swelling after surgery; three larger unpublished trials missed their goalsThe weakest case in the group
BromelainYes, in tiny amounts, in one study of 19 healthy menA small pain benefit after dental surgery; the one placebo-controlled knee arthritis trial was nullThe best characterized, and still modest
Bromelain, trypsin and rutoside blendsClaimed in a review written by a manufacturer consultantMatched diclofenac in arthritis trials that mostly lacked a placebo; large placebo trials were nullLargely manufacturer-sponsored evidence
NattokinaseOne 11-person pilot, intact enzyme not confirmedA modest drop of roughly 3 mmHg in systolic blood pressure in small, mostly short trials; a three-year trial in 265 lower-risk adults found no effect on artery thickness, blood pressure or lab measuresSee our full review
LumbrokinaseRat and laboratory work onlyAdd-on trials in hospitalized stroke patients, mostly Chinese and at high risk of biasDrug-setting evidence only

Evidence summaries describe research in people with diagnosed conditions and are not claims about what any supplement does for a healthy person.

Bromelain, from pineapple, is the one systemic enzyme with a clean human absorption study: in 19 healthy men taking 3 grams a day, intact and partly active bromelain was detectable in blood, though only in trace amounts. Meta-analyses of dental surgery trials agree on a small reduction in pain and disagree about swelling, and its one placebo-controlled knee arthritis trial found no benefit. Blends of bromelain, trypsin, and rutin, sold as Wobenzym and Phlogenzym, performed about as well as the painkiller diclofenac in arthritis trials that mostly had no placebo group and were largely sponsored by the manufacturer, and their largest placebo-controlled trials, in 721 people with ankle sprains, 301 people with multiple sclerosis, and 138 marathon runners, all came up empty. Older European formulas also contained papain and other enzymes, so check which formula a product actually uses. Nattokinase has a modest blood pressure signal, roughly 3 mmHg systolic in small, mostly short trials, but its best-run trial, three years in 265 healthy, lower-risk adults, found no effect on artery thickness, blood pressure, or anything else it measured, and lumbrokinase is studied mainly as an add-on drug for stroke in Chinese hospital trials at high risk of bias.

The through-line is that no systemic enzyme has a trial showing a meaningful health benefit in people without a diagnosed condition, and serrapeptase sits at the bottom of a group that is modest to begin with.

Safety, interactions, and who should skip it

In short trials of five days to a few weeks, serrapeptase generally causes side effects at rates similar to placebo, mostly stomach upset. Rarer reactions show up in case reports, mainly from Japan: several cases of lung inflammation, including eosinophilic pneumonia, and a blistering skin reaction that returned when the enzyme was restarted. A case of Stevens-Johnson syndrome occurred with a combination product that also contained diclofenac, which makes the cause uncertain. The 2013 systematic review found safety data lacking and no long-term data at all.

Check with a clinician first if any of these apply

You take a blood thinner such as warfarin or a newer anticoagulant, or an antiplatelet medicine such as aspirin or clopidogrel. You have had a blood clot, have a stent or heart disease, or are being treated for an infection. You have surgery or dental work scheduled. You are pregnant, where there is no safety data, or breastfeeding, where the only data is one small three-day trial from 1989 that reported no side effects in the mothers and no outcomes for the babies. You have a bleeding disorder, or you develop a new cough, breathlessness, or rash while taking it. No human study has tested serrapeptase alongside blood thinners. The one animal study that measured it found that oral serrapeptase repressed the clot-dissolving response in injured rats, which if anything points the wrong way for anyone at risk of clots, though what it does in people is unknown. Do not stop or change a prescribed blood thinner, heart medicine, or antibiotic to take it, and do not use it in place of treatment for a clot, heart disease, or an infection.

Regulators have taken notably different views. In the United Kingdom and the European Union, serrapeptase is treated as an unauthorized novel food: Food Standards Scotland advised in 2022 that supplements containing it be withdrawn, and the European Commission closed an application to authorize it that same year without approving it. Those are procedural decisions about food law rather than safety findings, but they explain why it can be hard to find there.

Frequently asked questions

Does serrapeptase actually work?

The honest answer is that it has not been shown to. The published evidence is six small placebo-controlled trials of serrapeptase on its own, the largest with 193 patients, and most of the positive findings are modest reductions in swelling after surgery. The one independent trial that compared it with placebo and with standard painkillers found it had no significant pain-relieving or anti-inflammatory effect. The largest placebo-controlled trials were run by its original manufacturer in Japan, enrolled 892 patients across three studies, all missed their main goals, and, as far as we can find, never appeared in a journal. Every condition studied was a medical one, so none of it tells you what the supplement does for a healthy person.

Why was serrapeptase withdrawn in Japan?

Takeda, which first brought serrapeptase to market in 1968, was required by Japanese regulators to prove it still worked. It ran three modern placebo-controlled trials, in chronic bronchitis and in ankle sprain, and none showed a statistically significant difference from placebo. At a January 2011 meeting, the Ministry of Health's re-evaluation committee asked for new trials. Its expert advisors noted problems with how the trials were run and said the results alone could not completely rule out an effect, but keeping the approval required proving one. Takeda chose to withdraw the drug instead, and generic makers followed. Singapore later stopped classifying serrapeptase as a medicine but still allows it in supplements.

Does serrapeptase dissolve arterial plaque or blood clots?

There is no evidence that it does either in people. A search of PubMed finds no human study of serrapeptase and arterial plaque at all. The popular claim that it digests only dead tissue, such as scar, clots, and plaque, while sparing healthy tissue, appears in reviews without a supporting citation and in sellers' accounts of unpublished observations. The one rat study that looked at the body's own clot-dissolving system found that oral serrapeptase repressed it rather than boosting it. Anyone with a clot, a stent, or heart disease should rely on treatment from their doctor, not an enzyme supplement.

Is serrapeptase absorbed into the bloodstream?

Nobody has shown that in humans. The evidence that it reaches the blood as an active enzyme comes from rat studies by its original manufacturer, using a dose of 100 milligrams per kilogram of body weight, which for an adult is roughly a gram as a human-equivalent dose, versus the 10 to 60 milligrams in a typical supplement. Enteric coatings that protect it from stomach acid open in the small intestine, which is exactly where the pancreas releases its own protein-digesting enzymes, and we found no study testing whether serrapeptase survives that.

Is serrapeptase better than bromelain?

If anything, the reverse. Bromelain, from pineapple, is the one systemic enzyme with a clean human study showing some of it reaches the blood intact, although only in trace amounts. It also has more trials, with meta-analyses agreeing on a small pain benefit after dental surgery. That is still a modest record, and its one placebo-controlled knee arthritis trial found no benefit over placebo, but it is more than serrapeptase can show.

Is serrapeptase safe?

Short trials of five days to a few weeks generally report side effects similar to placebo, mostly stomach upset. Rarer problems appear in case reports, mainly from Japan, including several cases of lung inflammation and a skin blistering reaction that returned when the enzyme was restarted. There is no long-term safety data, no data in pregnancy, and no human study of how it interacts with blood thinners. Because it is sold on the idea that it affects clotting, talk to a clinician before taking it if you use anticoagulant or antiplatelet medicines, are pregnant or breastfeeding, or have surgery coming up.

What does SPU on the label mean, and how much do trials use?

SPU and similar unit labels describe enzyme activity measured by how fast a sample digests casein, a milk protein. That test responds to any protein-digesting enzyme, brands do not use a harmonized unit, and we found no independent testing of whether commercial products contain what their labels claim. The trials dosed by weight instead, most often 10 milligram tablets taken three times a day, so a label's unit count cannot be reliably matched to a trial dose. This is a description of the research, not a recommendation.

Why is serrapeptase hard to buy in the UK and EU?

Because regulators there treat it as an unauthorized novel food, meaning there is no established history of people eating it before 1997 and it has not been approved as a new food ingredient. Food Standards Scotland advised in 2022 that supplements containing it should be withdrawn, and the European Commission closed an application to authorize it that same year without adding it to the approved list. These are procedural decisions rather than safety findings. In the United States it is sold as a dietary supplement.

The bottom line

Serrapeptase has a long history and a very short evidence base. The published trials are small and mostly measure swelling after surgery, the one independent trial that compared it head to head with placebo, standard painkillers, and a steroid found no significant pain-relieving or anti-inflammatory effect, and the largest trials ever run were conducted by the company that created it, failed, never appeared in a journal as far as we can find, and preceded its withdrawal in Japan. No human study shows that it reaches the bloodstream intact, and the claims about dissolving plaque, clots, and scar tissue have no human evidence behind them. If you are curious about systemic enzymes, bromelain has the better record, and it is still modest. For anything involving clots, heart disease, infection, or recovery from surgery, the answer is a conversation with your clinician rather than an enzyme capsule.

VS
Reviewed for accuracy by
Vladimir Salamakha

B.S. in Chemistry, University of South Florida · a formulation scientist with 15 years developing compliant, evidence-based products across nutritional supplements and personal care. More about the author →

A quick note This article is general information about research on serrapeptase and related enzymes, not medical advice. Every condition discussed here was studied in patients under medical care, and nothing in this article suggests that a supplement can diagnose, treat, cure, or prevent any disease. These products are not a substitute for treatment of blood clots, cardiovascular disease, infections, or post-surgical care. Talk to a qualified clinician before starting any supplement, especially if you take prescription medication.
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