BMJ Group Medical Reference
Botulinum toxin type A (brand names Botox and Dysport) is produced by certain bacteria. It works by blocking signals from your nerves. Doctors can inject tiny amounts of this toxin into a muscle to relax it. It can be injected into the muscles of the forearm (for a hand tremor) or into the muscles of the neck (for a head tremor).
Two studies of people who had hand tremor found that getting an injection of botulinum A into the forearm helped. The people got less tremor, and the effect lasted from one to three months.    But the injections didn't always help people with activities like eating.
The main side effect of botulinum A injection is hand weakness. Very rarely, botulinum toxin may spread from the place it has been injected. If you get any problems with swallowing, talking, or breathing after one of these injections, get medical help straight away. 
We need more research to say for certain whether this treatment can help.
Bacteria are tiny organisms. There are lots of different types. Some are harmful and can cause disease. But some bacteria live in your body without causing any harm.
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