All it takes are two little jabs. The first draws some blood from you, and the second reinjects it intramuscularly. Called autologous blood therapy, also known as autohaemotherapy, the procedure is said to activate your body's self-healing powers by means of external stimuli.

It sounds like a simple way to feel better, but does it really work? There's no conclusive answer, unfortunately, since convincing evidence from large-scale studies is lacking. But we've asked experts to clear up some other questions about autologous blood therapy.

What can the therapy be used to treat?

"Allergies and skin conditions such as acne or neurodermatitis, for example, or hives," says general practitioner Dr. Renate Schleker, chairperson of the Professional Association of Naturopathic Doctors in Germany (BAEN-D).

According to Schlecker, who provides the therapy herself at her surgery in the German city of Luebeck, it can also be effective in improving general health. "Someone who, for example, constantly catches colds can try to strengthen their immune system with autologous blood therapy," she says.

What methods are used in autologous blood therapy?

The blood can be reinjected right after being drawn, or the drawn blood can be processed before reinjection, for which a production authorization is required.

In platelet-rich plasma (PRP) therapy, the blood is run through a centrifuge to separate out the red and white blood cells. This leaves plasma – the yellowish fluid part of blood – and platelets, which are small cell fragments made in bone marrow that form clots to stop bleeding from blood vessel injuries and contain growth factors important in wound healing. The PRP is then reinjected.

"This therapy can stimulate healing in chronic wounds," says Dr. Stefanie Joos, medical director of the Institute for General Practice and Interprofessional Care at Tuebingen University Hospital in Germany and head of the research department of the German College of General Practitioners and Family Physicians (DEGAM).

The blood can also be treated with ozone or ultraviolet light, for instance, and then re-administered into the person, Schleker notes.

Another method involves drawing a drop of capillary blood from a person's fingertip and homeopathically diluting it. "Then it's placed on the tip of the patient's tongue or swallowed in a pellet," says Joos.

How does the body react to autologous blood therapy?

The reinjected blood acts as a stimulus. Your immune system reacts to it, perceiving it as a foreign body even though it's not. "In contrast to foreign blood – blood from another person, that is – there's no danger of harming your body," points out Schleker, who says autologous blood therapy can set beneficial immunological reactions in motion.

Are side effects possible?

Yes. Inflammation or mild redness can occur at the injection site, and hypersensitivity reactions are possible as well. "They're usually only temporary, however," Schleker says.

An elevated body temperature and mild infection symptoms can result too. And as with any intramuscular injection, there's a slight chance of an injection abscess if the needle hasn't been sufficiently sterilized and bacteria enter tissue.

Have any scientific studies been done on the efficacy of the therapy?

"Predominantly small-scale studies have shown the efficacy of administering unprocessed autologous blood," particularly in treating hives and skin disorders, says Schleker. Large-scale studies remain to be done. In other words, there's no conclusive evidence of efficacy.

In 2020, the web portal Medizin-Transparent.at, operated by Cochrane Austria, looked at studies on PRP therapies for osteoarthritis and concluded: "Injections with platelet-rich plasma could slightly reduce pain from osteoarthritis of the knee."

The therapy appeared to be more effective than placebo therapy, but only slightly. The studies tended to show no efficacy for PRP treatment of hip osteoarthritis.

Cochrane Austria is an entity of United Kingdom-headquartered Cochrane, an international, non-profit organization that links healthcare stakeholders and provides systematic medical reviews to facilitate healthcare decision-making.

In an article on autologous blood therapy published in 2021, Techniker Krankenkasse (TK), the largest health insurance fund in Germany, wrote: "Scientific proof of the efficacy of autologous blood therapy is lacking. There have been no acknowledged studies of this therapeutic method."

How much does autologous blood therapy cost?

In Europe, "you can expect to pay between 15 and 80 euros (about $17 to $91) per session," Schleker says. The amount depends in part on whether the blood is processed before reinjection. You typically have to cover the cost yourself, although some health insurers will pick up some or all of it.