Description
BTX-A is a type A neurotoxin, a large protein of bacterial origin. In research it is one of the longest-used tools for interrupting the transmission between nerve and muscle in a targeted and temporary way.
The mechanism is well described: the toxin binds to the endings of motor nerves, is taken up there and cleaves the protein SNAP-25. Without intact SNAP-25 the nerve endings can no longer release acetylcholine. The targeted muscle stays relaxed. The effect stays limited to the area around the application site and lasts until the nerve endings have formed new connections, typically several months in studies.
BTX-A has been studied most intensively in aesthetic research. The first observations on expression lines between the eyebrows date from 1992. Large placebo-controlled studies followed in the early 2000s. There is also a broad literature on neurological questions.
Potency is not stated in milligrams but in International Units (IU). These units are defined differently for each preparation and cannot be transferred one to one from one preparation to another.
You can order BTX-A as lyophilized powder in 10-vial packs with 100 IU per vial.
This information is for research and educational purposes only. No medical recommendations.
Risks & Safety
BTX-A is one of the most potent biological toxins known. Even the smallest amounts are active. The gap between the amounts used in studies and a dangerous amount is small. Its classification is therefore stricter than for almost any other product in the range.
Documented in studies, adverse event reports and case reports:
- Spread beyond the application site: the toxin can move away from where it was applied. Reported effects include drooping eyelids, double vision, dry mouth, difficulty swallowing and speaking, muscle weakness and shortness of breath, sometimes only days after application.
- Use outside medical settings: in a 2024 report by the US health agency CDC, seven women fell ill after such applications, four were hospitalized and two of them needed intensive care. In at least four cases the product was counterfeit.
- Units are not interchangeable: the IU values of different preparations are defined differently. Transferring values from studies can be off by a multiple.
- Local effects: headaches and temporarily drooping eyelids were the main observations in the controlled studies.
- Exclusions in the literature: disorders of neuromuscular transmission such as myasthenia gravis, pregnancy and breastfeeding.
- Loss of effect with frequent use: repeated applications at short intervals can trigger neutralizing antibodies, after which the effect wears off.
Risk tier 3, the strictest in the range. In the literature every application is performed by trained medical staff. This classification does not replace medical advice. Risk and responsibility for any actual use lie entirely with the buyer.
Studies
- Cleavage of the synaptic protein SNAP-25 by the type A neurotoxin - Nature 1993, Blasi et al: shows the mechanism by which acetylcholine release at the nerve ending is blocked.
- First observations on lines between the eyebrows - Journal of Dermatologic Surgery and Oncology 1992, Carruthers and Carruthers: the starting point of aesthetic research with the type A neurotoxin.
- Multicenter, placebo-controlled study on glabellar lines - Journal of the American Academy of Dermatology 2002, Carruthers et al: double-blind study on efficacy and tolerability against placebo.
- Adverse event reports to the US Food and Drug Administration - Journal of the American Academy of Dermatology 2005, Coté et al: analysis of reported adverse events in medical and cosmetic use.
- Illnesses after presumed counterfeit preparations - MMWR 2024, Thomas et al: seven illnesses after applications outside medical settings in Tennessee and New York City.
