Medical Encyclopaedia › Botulinum toxin (short definition)
In brief: Botulinum toxin is a nerve toxin produced by bacteria that is used in very small, purified amounts as a prescription-only medicine. It temporarily blocks signal transmission from the nerve to the muscle or to sweat glands.
How does it work?
Botulinum toxin prevents the release of the messenger substance acetylcholine at the nerve ending. The treated muscle relaxes, and treated sweat glands secrete less sweat. The effect sets in after a few days and wears off after about three to six months, because new nerve endings are formed.
Medical uses
Botulinum toxin is approved, among other things, for spasticity after stroke or in cerebral palsy, for dystonias such as torticollis or blepharospasm, for the prevention of chronic migraine, for overactive bladder and for severe underarm sweating.
Aesthetic use
In aesthetic medicine, it is used to temporarily smooth expression lines, such as frown lines, forehead lines or crow’s feet. Static wrinkles and volume loss are not treated by it. The treatment belongs in the hands of a doctor, requires information about benefits, risks and alternatives and should take realistic expectations into account.
Side effects and risks
Temporary redness, swelling, small bruises and headaches are common. If the active substance spreads into neighbouring muscles, an eyelid or eyebrow, for example, can droop for a few weeks. Very rarely, difficulty swallowing or breathing occurs, especially with high doses in medical use. It is not used during pregnancy and breastfeeding or in certain muscle and nerve diseases such as myasthenia gravis.
Important to know
Preparations from different manufacturers are not interchangeable in their dosage. Products from the internet or from non-medical providers may be counterfeit or contaminated and can cause severe poisoning.
Related terms in the encyclopaedia
Acetylcholine, Frown lines, Crow’s feet, Hyperhidrosis, Spasticity, Dystonia, Migraine, Overactive bladder, Ptosis
Sources
- Fachinformationen der in Deutschland zugelassenen Botulinumtoxin-Präparate, Bundesinstitut für Arzneimittel und Medizinprodukte (BfArM) und Europäische Arzneimittel-Agentur (EMA)
- Deutsche Gesellschaft für Neurologie (DGN): Leitlinien zu Dystonie und Spastik
- Robert Koch-Institut: RKI-Ratgeber Botulismus
Note: This article is for general information and does not replace advice, diagnosis or treatment from a doctor or pharmacist. Last updated: October 2026.