Therapies you may encounter — and what is known about them
Why this page exists
Every one of our routes ends with the same kind of sentence: this is not part of this route. A physician looked at the evidence and decided a therapy did not belong.
This page is where those therapies go. Not because they are worthless, and not to warn you off them — but because you are going to be offered them somewhere, and you should know what is actually known before you are.
What being on this page means, and what it does not.
Inclusion here means only that there is currently insufficient evidence for the reviewing physician to build a dedicated clinical pathway around a therapy.
It does not mean the therapy has been proven ineffective. Those are different statements, and the difference matters: some of what follows has real published benefit alongside real documented harm, and some has neither. Each entry says which.
Therapies can be added later if the evidence justifies it — and one can leave, if it earns a route of its own.
How each entry is organised. The same six questions, in the same order, for every therapy: what it is · why researchers are studying it · what research has found · what remains uncertain · what risks are documented · and who is unlikely to benefit. The order is deliberate. Every treatment in medicine — including every approved one — has negative trials and documented harms, and a page that leads with them teaches fear rather than understanding.
Exosomes
What they are. Tiny vesicles released by cells, carrying proteins and genetic material that cells use to signal to one another. The idea is to deliver that signal without delivering the cell.
Why researchers are studying them. Much of what a cell therapy appears to do may come not from the cell taking up residence, but from what it secretes. If that is true, the secreted signal could be produced, characterised and dosed like a product — no living cells to keep alive, no donor matching. That is a real biological question, and it is why the field is large: 66 clinical trials of MSC-derived vesicles were registered between 2014 and 2024.
What research has found so far. The strongest human evidence is in skin. A 2025 systematic review in dermatology found scar thickness reduced by 32.5% against 19.9% in controls, with elasticity improving 11.3% where controls worsened. In androgenetic alopecia, a prospective study found hair density increased significantly at four and twelve weeks. In critically ill patients with ARDS, one trial reported mortality of 19% against 54%.
How certain is that? These are early trials, several small, and the products differ from one another. A result with one preparation is not evidence for a different vial.
What remains uncertain. In wound healing there are no completed human trials at all — the only pooled analysis is of animal studies. Across the field, the preparations are not standardised, so dose and content vary between products with the same name.
What risks are documented. These come from case reports and small series — they describe what has happened to specific patients, not what typically happens:
- Delayed-onset granulomas in seven to eight women aged 26 to 52, after intradermal injection for cosmetic purposes.
- Four further women with persistent redness, nodules and granulomatous inflammation.
- Skin necrosis after injection of a lyophilised formulation.
- In 2019, the FDA issued a public safety notification after patients in Nebraska developed serious infections from an unapproved product. Fewer than five people became ill, within a two-month window; the state Attorney General later sued the clinic. The infections were traced to manufacturing, not to the concept.
No exosome product is approved by the FDA for any use.
Who is unlikely to benefit. Anyone whose question is about wound healing — there is no human trial to draw on. And anyone being offered a product whose preparation, dose and content cannot be described to them.
Intravenous vitamin C
What it is. Vitamin C given intravenously, at doses far above what can be reached by mouth.
Why researchers are studying it. At those doses vitamin C stops behaving like an antioxidant and acts as a pro-oxidant — generating hydrogen peroxide in tissue. Laboratory work suggests cancer cells may be less able to clear it than normal cells. That is the biological question the trials are testing, and it is also why the oral form is not the same thing.
What research has found so far. A phase 2 trial in pancreatic cancer reported median overall survival of 16 months with chemotherapy plus high-dose IV vitamin C, against 8 months with chemotherapy alone. Safety is reassuring at scale: minimal adverse events among roughly 10,000 people treated annually.
What remains uncertain. A great deal. In prostate cancer, high-dose IV vitamin C added to docetaxel did not improve PSA response, progression-free survival or quality of life, and the trial stopped for futility. Independent reviewers describe the high-quality clinical evidence in oncology as limited.
What risks are documented. The one that matters most is timing, not toxicity: Memorial Sloan Kettering states explicitly that vitamin C should be avoided during radiation therapy. The pro-oxidant mechanism above is exactly why an interaction question is real.
Who is unlikely to benefit. Anyone in active radiotherapy, until their oncologist has been asked. And anyone expecting the oral form to do the same thing — it cannot reach the same blood levels.
NAD and intravenous vitamin infusions
What they are. Infusions of NAD precursors, B vitamins or mixed formulations, given for fatigue, recovery and general wellbeing.
Why researchers are studying them. NAD is genuinely central to how cells produce energy, and its levels fall with age. The biological rationale is real; what is missing is the evidence that infusing it changes anything a patient would notice.
What research has found so far. In this category, little in the way of controlled human outcomes. The strongest published work in the family is elsewhere: alpha lipoic acid intravenously, 600 mg daily for three weeks, produces a significant and clinically relevant improvement in diabetic neuropathy — a specific problem, not a general one.
What remains uncertain. Whether infusion adds anything over oral supplementation for people who are not deficient.
What risks are documented. An injectable NAD product was voluntarily recalled in July 2025, and in October 2025 the FDA classified that recall as Class 1 — the category reserved for products with a reasonable probability of serious harm or death. Intravenous B-complex carries documented warnings: urticaria, breathing difficulty, wheezing, angioedema, and rare anaphylaxis.
The pattern here is not «vitamins are dangerous». It is that an injection is a different object from a supplement: the risk belongs to the route and the manufacturing, not to the molecule.
Who is unlikely to benefit. Anyone who is not deficient, and anyone whose alternative is the same compound by mouth.
Thymic peptides and transfer factor
What they are. Products intended to modulate immune function — some defined synthetic molecules, some extracts.
Why researchers are studying them. The immune system genuinely can be modulated, and one of these products proves it: thymalfasin, a defined 28-amino-acid synthetic peptide, is an approved prescription medicine in more than 30 countries for hepatitis B and C, with complete virological response of 40.6% against 9.3% in its pivotal work and a safety record across more than 11,000 subjects in over 30 trials.
What remains uncertain — and the trap is identity, not efficacy. Three chemically distinct things are routinely called the same: thymalfasin, a crude thymic extract, and anything labelled «thymic peptide». An approval belongs to one specific molecule and does not transfer to a different vial with a similar name.
And the effect itself is fragile: a 2025 meta-analysis found a pooled benefit that disappeared when restricted to high-quality studies, and the largest phase 3 trial was negative — 28-day mortality 23.4% against 24.1%.
On transfer factor: most clinical evidence originates with the manufacturer, and robust independent replication is missing.
What risks are documented. For thymalfasin, a well-tolerated profile across a large exposed population. For undefined extracts, the risk is that nobody can tell you what is in them.
Who is unlikely to benefit. Anyone being offered an undefined «thymic» product on the strength of thymalfasin’s approval. That approval is not about the product in front of them.
Placental extract
What it is. An extract of human placenta, given by injection.
Why researchers are studying it. It is approved as a pharmaceutical in Japan, which means a regulator has reviewed a dossier for it — an unusual position for a product of this kind.
What research has found so far. Its approved indication there is narrow: liver function — considerably narrower than what is commonly marketed.
What remains uncertain. Whether anything outside that indication is supported.
What risks are documented. A consequence almost nobody is told: people who have received human placental extract are permanently excluded from donating blood.
Who is unlikely to benefit. Anyone being offered it for something other than its approved indication — which is most of what it is offered for.
Stromal vascular fraction and adipose-derived products
What they are. A mixed cell population obtained by processing a patient’s own fat and injecting it back.
Why researchers are studying them. The cells are the patient’s own, available in quantity, and obtainable in a single procedure. That removes donor matching and much of the manufacturing question — which is why the approach attracted so much clinical interest.
What research has found so far. For knee osteoarthritis, an independent Cochrane review of stem cell injections rated the certainty of the evidence low to very low, and was uncertain whether they improve quality of life or treatment success against placebo.
What remains uncertain, and how we know it is uncertain. The same review found up to three larger randomised trials conducted and withdrawn before reporting, which is what suspected publication bias looks like from the outside. A pivotal randomised trial of one device system was registered and has published no results. Radiographic progression was not assessed in any included study.
What risks are documented. The FDA names adipose-derived products, including stromal vascular fraction, among regenerative products it has not approved (Consumer Alert, 22 July 2020).
Who is unlikely to benefit. Anyone expecting the certainty that the volume of use implies. The evidence has not kept pace with the marketing.
The one question that covers all of them
What has been published on THIS preparation — not on this category?
An approval, a trial or a safety record belongs to one specific product, made one specific way. Everything on this page has something published about the category. That is not the same as evidence about the vial you are being offered, and telling the difference is the single most useful thing you can do.
Questions worth asking your physician
- Is there published human evidence for this specific preparation, or only for the category?
- What is the most likely realistic outcome for someone in my situation — not the best case reported?
- What would you expect to happen if I did nothing?
- What would make you tell me this is not appropriate for me?
- Is there an interaction with anything I am currently taking or receiving?
The first step is not a commitment. It is a conversation, and then a review. You can stop at any point, and you can ask us to delete your information at any time.
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