Botox (onabotulinumtoxinA) is a prescription drug that’s used to treat a variety of medical conditions. Botox comes as a powder that’s mixed with liquid to form a solution, which is injected.

Botox is used for medical purposes in adults and some children. Some of its uses include:

To learn more, see the “What is Botox used for?” section.

Botox basics

The active ingredient in Botox is called onabotulinumtoxinA, which is a biologic medication. A biologic is made from parts of living organisms. Botox’s active ingredient is not available in a biosimilar form. (Biosimilars are like generic drugs. But unlike generics, which are made for nonbiologic drugs, biosimilars are made for biologic drugs.)

Note: This article discusses Botox, which is used for medical purposes. It does not cover Botox Cosmetic, the version of Botox that’s used for cosmetic reasons.

If you have certain conditions, your doctor may recommend Botox. It’s used for:

For bladder-related conditions, doctors can prescribe Botox for people who can’t take anticholinergic drugs or whose condition didn’t respond to anticholinergic drugs.

With all the conditions Botox treats, nerves send signals that cause symptoms such as muscle contractions, sweating, or pain. Botox works by preventing nerves from sending signals that trigger these symptoms.

It’s important to note that Botox is not used to treat:

  • episodic migraine (in which migraine episodes occur on 14 or fewer days per month)
  • excessive sweating in areas other than the armpit

The manufacturer of Botox warns that using this drug for conditions that the Food and Drug Administration (FDA) has not approved could lead to serious side effects. For more information, see the next section.

Also, you should not use Botox interchangeably with other botulinum toxin products.

Like most drugs, Botox may cause mild or serious side effects. The following lists describe some of the more common side effects. These lists don’t include all possible side effects. Side effects from Botox can be different for each of the drug’s uses.

Your doctor or pharmacist can tell you more about the potential side effects of Botox. They can also suggest ways to help reduce side effects.

Mild side effects

Here’s a list of some of the mild side effects that Botox can cause. To learn about other mild side effects, talk with your doctor or pharmacist, or read Botox’s prescribing information.

Side effects of Botox can vary depending on where the drug is injected. Mild side effects can include:

For more information about some of these side effects, see the “Side effect focus” section.

Mild side effects of many drugs may go away within a few days to a couple of weeks. But if they become bothersome, talk with your doctor or pharmacist.

Serious side effects

Serious side effects from Botox can occur, but they aren’t common. They can vary depending on the condition being treated.

If you have serious side effects from Botox, call your doctor right away. But if you think you’re having a medical emergency, you should call 911 or your local emergency number.

Serious side effects can include:

In studies, an overreaction of the nervous system was more likely in people receiving Botox for loss of bladder control that’s related to a disorder of the nervous system.

For more information about some of the listed side effects, see the “Side effect focus” section.

Note: The manufacturer of Botox warns that using this drug for conditions that haven’t been approved by the Food and Drug Administration (FDA) could lead to serious side effects. Examples include excessive weakness, difficulty swallowing, and aspiration pneumonia (an infection caused by accidentally inhaling substances such as food). To learn about the FDA-approved uses of Botox, see the “What is Botox used for?” section.

Side effect focus

Learn more about some of the side effects Botox may cause.

Pain after injection

You may have some pain after receiving Botox injections. In fact, this was a common side effect in studies of the drug. The pain typically occurs around Botox injection sites, which could include areas on your back, neck, arms, or legs.

What might help

To help relieve pain after Botox injections, try the following:

  • Avoid rubbing or massaging the skin around or on the injection site.
  • Apply a cold compress to the injection site.
  • Take over-the-counter pain relievers such as acetaminophen (Tylenol) or ibuprofen (Advil) if your doctor says it’s fine to do so.

If you have pain that’s severe or bothersome after getting Botox injections, talk with your doctor.

Spread of toxin effects

Botox has a boxed warning about the risk of the spread of toxin effects. A boxed warning is the most serious warning from the Food and Drug Administration (FDA).

When it’s injected into your body, Botox may spread outside of the area where you receive the injection. This can lead to symptoms that are similar to botulism poisoning. These symptoms may include:

These symptoms might happen within hours of getting a Botox injection. Or, they might not happen until weeks after you’ve had a Botox injection. Your risk of having difficulty breathing or swallowing is higher if you already have either breathing or swallowing problems.

What might help

If you have any of the symptoms listed previously after getting a Botox injection, tell your doctor right away. Call 911 or your local emergency number if your symptoms feel life threatening.

Urinary tract infection

You might get a urinary tract infection (UTI) after getting Botox. In studies, this side effect was more common in people who received Botox to treat overactive bladder than in people receiving the drug for other conditions.

A few possible symptoms of UTI include:

What might help

If you have any UTI symptoms after getting a Botox injection, tell your doctor. Prescription drugs such as antibiotics, antivirals, or antifungals are usually needed to treat UTIs. But to help lessen UTI symptoms, you can also try home remedies such as drinking water and cranberry juice.

Allergic reaction

Some people may have an allergic reaction to Botox. Symptoms of a mild allergic reaction can include:

  • rash
  • itchiness
  • flushing (temporary warmth, redness, or deepening of skin color)

A more severe allergic reaction is rare but possible. Symptoms of a severe allergic reaction can include swelling under your skin, typically in your eyelids, lips, hands, or feet. They can also include swelling of your tongue, mouth, or throat, which can cause difficulty with breathing.

Call your doctor right away if you have an allergic reaction to Botox. Call 911 or your local emergency number if your symptoms feel life threatening.

Find answers to some commonly asked questions about Botox.

How long does it take Botox to work?

Botox starts working within 1 to 3 days after it’s injected into your body. However, it might be several weeks after your injection before you notice your condition improving.

Is Botox used for tension headaches?

Yes, Botox is sometimes prescribed to treat tension headaches. But the Food and Drug Administration (FDA) hasn’t approved Botox to treat tension headaches, so this is known as an off-label use.

If you have questions about treatment options for tension headaches, talk with your doctor.

How often can you get Botox injections?

How often you’ll be able to get Botox injections depends on the condition it’s being used to treat. In general, you’ll get Botox injections only once every 3 months. Your doctor will recommend how often you should receive Botox.

Your doctor will recommend the dosage of Botox that’s right for you. The following text discusses commonly used dosages, but the dosage you receive will be determined by your doctor.

Forms and strengths

Botox is given as an injection into your body by a healthcare professional. For most of its uses, you’ll get Botox as an injection into a muscle or into multiple muscles. But the type of injection and exact injection sites vary depending on the condition you’re receiving the drug for.

Botox comes as a powder inside vials. The powder is mixed with liquid to make a solution for injection. The drug is available in two strengths: 100 units and 200 units.

Recommended dosages

Your doctor will recommend the dosage of Botox that’s right for you. The following text discusses commonly used dosages for adults, but the dosage you receive will be determined by your doctor. For information on Botox dosages for children, see the “Children’s dosages” section.

Dosage for migraine episodes

To prevent migraine episodes due to chronic migraine, you’ll receive 155 units of Botox. This dose is divided across 31 different injection sites in certain muscles of your head or neck. You may receive these injections every 3 months.

Dosage for excessive eye blinking

Botox may be used to treat excessive eye blinking that’s related to involuntary muscle spasms. For this use, you’ll receive 1.25 to 2.5 units of Botox in certain muscles in the upper and lower eyelid of the affected eye. You’ll likely receive these injections every 3 months.

If the recommended dosage isn’t helping to treat your symptoms, your doctor may increase your Botox dosage by up to 5 units for each injection site. The maximum dosage for treating excessive eye blinking is 200 units per month.

Dosage for muscle spasms in the neck

For treating involuntary muscle spasms in the neck, the Botox dosage varies depending on several factors. These include the position of your head and neck and where the muscle spasms occur. The recommended Botox dose for this condition is 50 units per injection site. You may receive injections every 3 months.

If you’ve never had Botox injections, your doctor will likely start you at a lower dosage. They may increase the dosage if you respond well to the drug.

Dosage for excessive armpit sweating

For treating severe excessive armpit sweating, your dose of Botox will be 50 units per injection site. You’ll receive 10 to 15 injections in different areas of each armpit. Your doctor will recommend how often you should receive injections for your condition.

Dosage for muscle spasticity

Botox may be used to treat muscle spasticity in the arms or legs.

For treating muscle spasticity in your arms, you’ll receive 75 to 400 units of Botox across up to 18 sites in different muscles. For treating muscle spasticity in your legs, you’ll receive 300 to 400 units of Botox across 16 sites in different muscles.

Your doctor will recommend how often you should receive Botox for muscle spasticity. However, you likely won’t receive injections more often than every 3 months.

Dosage for crossed or misaligned eyes

For crossed or misaligned eyes, you’ll receive 1.25 to 5 units of Botox in the affected muscles.

After 1 to 2 weeks, your doctor will examine your eyes. Depending on how well the drug worked for your condition, your doctor may increase your Botox dose. The maximum dose in this case is 25 units per muscle.

The effect of Botox will decrease over 2 to 6 weeks. Your doctor may suggest additional injections for crossed or misaligned eyes as needed.

Dosage for overactive bladder

Botox is prescribed to treat an overactive bladder with loss of bladder control and frequent or urgent urination. For this purpose, the recommended dose is 100 units, divided into 20 injections into the muscle wall of the bladder. The maximum dose for an overactive bladder is 100 units.

Your doctor will recommend how often you should receive Botox for overactive bladder. However, you likely won’t receive injections more often than every 3 months.

Dosage for loss of bladder control

Botox is used to treat loss of bladder control that’s related to a disorder of the nervous system. For this use, you’ll receive 200 units of Botox, divided into 30 injections into the muscle wall of your bladder. The maximum dose for loss of bladder control is 200 units.

Your doctor will recommend how often you should receive Botox for loss of bladder control. However, you likely won’t receive injections more often than every 3 months.

Children’s dosages

The following discusses the recommended dosages of Botox for the conditions it’s used for in children. However, your child’s doctor will recommend the right dosage for your child.

Children’s dosage for excessive eye blinking or crossed or misaligned eyes

The dosage of Botox for children ages 12 years and older with either eye condition is the same as it is for adults. See the “Dosage for excessive eye blinking” and “Dosage for crossed or misaligned eyes” sections earlier for details.

Children’s dosage for muscle spasticity in the arms or legs

The dosage of Botox for children ages 2 years and older with muscle spasticity depends on their body weight in kilograms (kg). Note that 1 kilogram is about 2.2 pounds (lb).

For treating muscle spasticity in the arms, a child will receive 3 to 6 units per kg of body weight (units/kg) across up to 16 sites in different muscles. The maximum dose for this use is 6 units/kg or 200 units, whichever is lower.

For treating muscle spasticity in the legs, a child will receive 4 to 8 units per kg of body weight (units/kg) across up to eight sites in different muscles. The maximum dose for this use is 8 units/kg or 300 units, whichever is lower.

For a child receiving treatment for muscle spasticity in both their arms and legs, the total dose in a 3-month period should not exceed 10 units/kg or 340 units, whichever is lower.

Your child’s doctor will recommend how often your child should receive Botox for muscle spasticity. However, they likely won’t receive injections more often than every 3 months.

Children’s dosage for loss of bladder control

The dosage of Botox for children ages 5 years and older with loss of bladder control who weigh 34 kg (about 75 lb) or more is the same as it is for adults. For more information, see the “Dosage for loss of bladder control” section.

For children weighing less than 34 kg, the recommended dosage is 6 units/kg.

Your child’s doctor will recommend how often your child should receive Botox for loss of bladder control. However, they likely won’t receive injections more often than every 3 months.

Questions about Botox’s dosage

Here are some common questions about Botox’s dosage.

  • What if I miss a dose of Botox? Call your doctor’s office to reschedule any missed appointments for Botox injections. The staff at your doctor’s office can help you set up another appointment.
  • Will I need to receive Botox long term? Yes, in most cases, you’ll receive Botox long term for your condition. But be sure to talk with your doctor about this.
  • How long does Botox take to work? Botox starts working within a few days after it’s been injected into your body. But it might be several weeks after the injection before you notice your condition improving.

Your doctor will explain how Botox is given. They’ll also explain how often you should get Botox for your condition.

Depending on the condition you’re using Botox to treat, you may need to prepare for your injection. For example, if you have excessive armpit sweating, you may need to shave the area and avoid using deodorants in the 24 hours before your appointment.

Your doctor may recommend general anesthesia if you’re receiving injections in certain areas, such as your bladder.

Your doctor will let you know how to prepare for your appointment and what to expect when you receive your Botox injections. Be sure to follow your doctor’s instructions for when to receive Botox.

Getting Botox

Botox comes as a powder inside vials. The powder is mixed with liquid to make a solution that’s injected into your body. You’ll get Botox injections from a healthcare professional.

For most uses, you’ll get Botox as an injection into the muscle. But the type of injection and exact injection sites for Botox vary depending on the condition you’re receiving the drug for.

For example, for migraine episode prevention, you’ll get Botox in these injection sites:

  • your forehead
  • your temples
  • back of your head
  • base of your neck
  • between your shoulders

But injection sites for overactive bladder (OAB) are very different. For OAB, you’ll get Botox injections directly into the muscle wall of your bladder.

Botox and food

Botox is given as an injection. You can get Botox with or without having eaten any food.

Here are a few important considerations to keep in mind before you use Botox.

Interactions

Taking medications, vaccines, foods, and other things with a certain drug can affect how the drug works. These effects are called interactions.

Before receiving Botox, be sure to tell your doctor about all medications you take (including prescription and over-the-counter types). Also, describe any vitamins, herbs, or supplements you use. Your doctor or pharmacist can tell you about any interactions these items may cause with Botox.

Interactions with drugs or supplements

Botox can interact with several types of drugs, including:

This list doesn’t contain all types of drugs that may interact with Botox. Your doctor or pharmacist can tell you more about these interactions and any others that may occur with use of Botox.

Boxed warning

Botox has a boxed warning. A boxed warning is the most serious warning from the Food and Drug Administration (FDA) about drug effects that may be dangerous.

Botox may spread outside of the area where you receive the injection. This can lead to symptoms that are similar to botulism poisoning. These symptoms may include:

For details, see the “What are Botox’s side effects?” section.

Other warnings

Botox can sometimes cause harmful effects in people who have certain conditions. This is known as a drug-condition interaction. Other factors may also affect whether Botox is a good treatment option for you.

Talk with your doctor about your health history before you take Botox. Be sure to tell them if any of the following factors apply to you:

  • infection at an injection site
  • neuromuscular disorders, such as myasthenia gravis
  • difficulty breathing or swallowing
  • difficulty emptying your bladder
  • a history of bleeding problems
  • planned surgery
  • allergic reaction

Use with alcohol

There aren’t any known issues with drinking alcohol during Botox treatment.

Keep in mind that alcohol can make you bleed more easily than usual. And bleeding is a possible side effect of Botox injections. You may need to avoid drinking alcohol for a few days before your injections.

If you drink alcohol, talk with your doctor about the amount that’s safe for you to drink during Botox treatment.

Pregnancy and breastfeeding

If you can become pregnant, are breastfeeding, or are using birth control, it’s important to consider whether Botox is a safe choice for you. Your doctor can discuss this with you.

As with any prescription drug, the cost of Botox can vary depending on many factors. These factors include your treatment plan, your insurance coverage, and other factors. To find current prices for Botox injections in your area, talk with your doctor.

You won’t pick up Botox from a pharmacy. The drug is only sold by specialty pharmacies, and you’ll get Botox injections at your doctor’s office.

You can visit the Botox website to view possible support options, including a Botox savings program.

If you have questions about how to pay for your treatment, you can talk with your doctor or pharmacist.

Q:

If I use Botox Cosmetic for cosmetic purposes, will it help prevent migraine episodes as well?

Anonymous

A:

It’s unlikely that Botox Cosmetic will help prevent migraine episodes. The number of injection sites and the doses given are much higher for helping prevent migraine episodes than for cosmetic purposes.

There may be some similarities in the injection sites used. But the approved dose of Botox for migraine is 155 units given across seven different areas in your head and neck muscles. The approved dose of Botox Cosmetic is 20 to 40 units given in the specific areas desired.

Note that the manufacturer of Botox and Botox Cosmetic warns against using these drugs for conditions other than what the FDA has approved for these drugs. So, it’s not recommended to use Botox Cosmetic for treating conditions the FDA has approved Botox for, such as preventing migraine episodes.

If you’re interested in receiving Botox to help prevent migraine episodes, talk with your doctor to see whether Botox is right for you.

The Healthline Pharmacist TeamAnswers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.

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