context: Many people know botulinum toxin for its power to treat wrinkles. ( Think Botox.) But the medication also helps those with multiple sclerosis ( MS) who have spasticity -- stiff muscles and sudden, uncontrollable movements -- in their arms. The drug is one option you and your doctor can consider as part of your MS treatment. Botulinum toxin is a muscle-relaxing medication that's made from bacteria called Clostridium botulinum. There are four types: Onabotulinumtoxin A ( Botox/ Botox Cosmetic) Rimabotulinumtoxin B ( Myobloc) Abobotulinumtoxin A ( Dysport) Incobotulinumtoxin A ( Xeomin) These drugs also treat other problems, including a condition in which the neck muscles contract over and over (cervical dystonia), migraine headaches, and blinking you can't control (blepharospasm). Botox is the drug that people use to smooth wrinkles. Normally, your nerves send electrical messages to your muscles so they will move when you want them to. These messages travel from the nerves to the muscles via a chemical called acetylcholine. But if you have MS, the disease damages the nerves and throws those signals out of sync. It makes your muscles tense up and move when you don't want them to. Botulinum toxin blocks acetylcholine, which lets the muscle relax. That makes it easier to move and use your limbs and eases any stiffness and pain you might feel. You get botulinum toxin as a shot into your muscle with a very fine needle. You'll need to go to your doctor's office to get the treatment. The medication doesn't travel throughout the body, so your doctor will need to give you several shots at once. Where you get them depends on which muscles are giving you the most trouble. If the muscles are small or hard to reach, your doctor may need to record electric signals from them to make sure he's treating the right ones. The medicine usually doesn't sting, but some people report minor pain from the injection. It usually goes away quickly. You'll notice that the drug starts to work after 1-2 weeks. Your muscles should start to relax. One dose usually works for 2-6 months. So you may have to go back to your doctor for more injections to keep getting the benefits of the treatment. There's a limit to how much botulinum toxin you can get at once. So it might not be a good choice for you when spasticity affects many of your muscles or when the spastic muscles are large, like those in your legs. Your doctor will keep track of your symptoms to see if the treatment is working. Botulinum toxin might cause: Weakness in the muscle and the ones near it after an injection that may keep you from using those parts of your body. The problem doesn't last long. It's rare, but some people get flu-like symptoms 1 week after the injections. They usually only last for about a day. It's rare, but some people's immune systems make things called antibodies that keep botulinum toxin from working as well as it should. To keep this from happening, your doctor won't give you injections more often than every 3 months. Coverage varies greatly. Check with your insurance company before treatment begins. If you think that the medication is not working. ( But wait at least 2 weeks after you get the injections.) If you are having side effects that you think may be related to botulinum toxin. When the effects of the medication wear off.