Botox injections are noted primarily for the ability to reduce the appearance of facial wrinkles. They’re also used to treat conditions such as neck spasms (cervical dystonia), excessive sweating (hyperhidrosis), an overactive bladder and lazy eye. Botox injections may also help prevent chronic migraines.

Botox injections use a toxin called onobotulinumtoxinA to temporarily prevent a muscle from moving. This toxin is produced by the microbe that causes botulism, a type of food poisoning.

Botox was the first drug to use botulinum toxin. Other products now include abobotulinumtoxinA (Dysport), rimabotulinumtoxinB (Myobloc) and incobotulinumtoxinA (Xeomin). Each is a little different, particularly when it comes to dosage units, so they aren’t interchangeable.

Botox injections block certain chemical signals from nerves, mostly signals that cause muscles to contract. The most common use of these injections is to temporarily relax the facial muscles that cause wrinkles in the forehead and around the eyes. Botox injections are also used to treat conditions that affect how the body functions. Examples include:

• Cervical dystonia: In this painful condition, your neck muscles contract involuntarily causing your head to twist or turn into an uncomfortable position.
• Lazy Eye: The most common cause of lazy eye is an imbalance in the muscles responsible for positioning the eye.
• Muscle contractures: Some neurological conditions, such as cerebral palsy, can cause your limbs to pull in toward your center. In some cases, these contracted muscles can be relaxed with Botox injections.
• Hyperhidrosis:  In this condition, excessive sweating occurs even when the temperature isn’t hot and you’re not exerting yourself.
• Chronic migraine: If you experience migraines more than 15 days a month, Botox injections may help reduce headache frequency.
• Bladder dysfunction: Botox injections can also help reduce urinary incontinence caused by an overactive bladder.
• Eye twitching: Botox injections may help relieve contracture or twitching of muscles around the eye.

Botox injections are relatively safe when performed by an experienced doctor. Possible side effects and complications include:

• Pain, swelling or bruising at the injection site
• Headache or flu-like symptoms
• Droopy eyelid or cockeyed eyebrows
• Crooked smile or drooling
• Eye dryness or excessive tearin

Although very unlikely, it’s possible for the toxin in the injection to spread in your body. Call your doctor right away if you notice any of these effects hours to weeks after receiving Botox:

• Muscle weakness
• Vision problems
• Trouble speaking or swallowing
• Breathing problems
• Loss of bladder control

Doctors generally recommend against using Botox when you’re pregnant or breast-feeding. And Botox should not be used in people who are allergic to cow’s milk protein.

Tell your doctor if you’ve had any type of Botox injection within the past four months. Also tell your doctor if you take muscle relaxants, sleeping aids or allergy medications. If you take blood thinners, you may need to stop taking them several days before your injection to reduce your risk of bleeding or bruising.

Most people don’t feel much discomfort during the procedure. But you may want your skin numbed beforehand, especially if your palms or soles are being treated for excessive sweating. Your doctor might use one or more of various methods available to numb the area, such as topical anesthesia, ice and vibration anesthesia, which uses massage to reduce discomfort.

Botox injections are usually performed in a doctor’s office. Your doctor uses a thin needle to inject tiny amounts of botulinum toxin into your skin or muscles. The number of injections needed depends on many factors, including the extent of the area being treated.

Do not rub or massage the treated areas for 24 hours. This may help prevent the toxin from spreading to a different area. You can return to your normal activities right after the procedure.

Botox injections usually begin working one to three days after treatment. Depending on the problem being treated, the effect may last three months or longer. To maintain the effect, you’ll need regular follow-up injections.