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OnabotulinumtoxinA (Botox/Botox Cosmetic)

Pronunciation: on-a-bot-u-line-um tox-in A
Generic name: OnabotulinumtoxinA
Brand names: Botox, Botox Cosmetic
Dosage form: vial, single-use
Drug class: Skeletal muscle relaxants

Medically reviewed by Carmen Pope, BPharm. Last updated on Apr 16, 2024.

What is onabotulinumtoxinA?

OnabotulinumtoxinA is an injectable botulinum toxin type A preparation that may be used for certain medical conditions or to improve appearance. There are 2 different formulations of onabotulinumtoxinA: Botox and Botox Cosmetic. Each contains the same active ingredient (onabotulinumtoxinA) but the number of dosage units per vial and FDA-approved uses differ, and they are not interchangeable.

Botox is FDA-approved to treat certain medical conditions, specifically:

Botox is also approved to prevent headaches in adults with chronic migraine (at least 15 headache days per month) whose headaches last 4 hours a day or longer.

Botox Cosmetic is FDA-approved for the temporary improvement in the appearance of:

You may receive treatment for frown lines, crow’s feet lines, and forehead lines at the same time.

OnabotulinumtoxinA is a neurotoxin that works by blocking the release of a neurotransmitter called acetylcholine, which prevents muscle contraction in the area injected, causing the muscles to relax. In small, localized doses, this can treat a range of medical conditions, such as muscle spasms, detrusor muscle contraction, and excessive sweat gland activity, as well as reduce skin wrinkles. The effect is only temporary because extra nerve endings and acetylcholine receptors develop.

Botox and Botox Cosmetic were first FDA-approved on December 9, 1991.

What are the side effects of onabotulinumtoxinA?

OnabotulinumtoxinA (Botox/Botox Cosmetic) may cause serious side effects, see warnings below.

Get emergency medical help if you have signs of an allergic reaction: hives, itching; wheezing, difficulty breathing; feeling like you might pass out; swelling of your face, lips, tongue, or throat.

Other side effects may include:

Tell your doctor if you have any side effect that bothers you or that does not go away. These are not all the possible side effects of onabotulinumtoxinA (Botox/Botox Cosmetic). For more information, ask your doctor or pharmacist. Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA1088.

Warnings and serious effects

OnabotulinumtoxinA may cause serious side effects that can be life-threatening. These problems can happen hours, days, to weeks after an injection of Botox or Botox Cosmetic. Call your doctor or get medical help right away if you have any of these problems after treatment:

Seek immediate medical attention if respiratory, speech, or swallowing difficulties occur.

Due to different potency units, Botox and Botox Cosmetic are not interchangeable with other botulinum toxin products, such as Myobloc, Dysport, Xeomin, Daxxify, Letybo, or Jeuveau.

Botox and Botox Cosmetic must be administered by a trained healthcare provider and only for FDA-approved indications. Potential serious side effects may occur with unapproved uses.

People with preexisting neuromuscular disorders or compromised respiratory function may be more at risk of side effects. When used to treat blepharospasm, corneal exposure and ulceration due to reduced blinking may occur with Botox treatment. Eye and retinal problems may also occur. Your healthcare provider will monitor you for these.

You should not receive Botox if you have an infection in the area where the medicine will be injected. This medicine should not be used to treat overactive bladder or incontinence if you have a current bladder infection or if you are unable to urinate (unless you routinely use a catheter).

It is not known whether Botox is safe and effective in people younger than:

It is not known whether Botox is safe and effective in preventing headaches in people who have less than 14 headache days each month (episodic migraine) or for severe sweating anywhere other than the armpits.

It is not known whether Botox Cosmetic is safe and effective in people younger than 18 years of age or for use more than once every 3 months.

Before taking

Do not receive onabotulinumtoxinA (Botox/Botox Cosmetic):

Tell your doctor about all your medical conditions, including if you:


Based on animal data, onabotulinumtoxinA (Botox/Botox Cosmetic) may harm your unborn baby. Talk to your healthcare provider about the risks involved with receiving onabotulinumtoxinA during pregnancy.


It is not known if onabotulinumtoxinA (Botox/Botox Cosmetic) passes into breast milk. Talk to your healthcare provider about the best way to feed your baby.

How is onabotulinumtoxinA (Botox/Botox Cosmetic) administered?

OnabotulinumtoxinA (Botox/Botox Cosmetic) injections should be given only by a trained medical professional, even when used for cosmetic purposes.

Your healthcare provider may change your dose until the best dose for you is found.

The effects of an onabotulinumtoxinA injection are temporary. Your symptoms may return completely within 3 months. After repeat injections, it may take less and less time before your symptoms return, especially if your body develops antibodies to the botulinum toxin.

Do not seek botulinum toxin injections from more than one medical professional at a time. If you switch healthcare providers, tell your new provider how long it has been since your last botulinum toxin injection.

Other dosage information

Injections may be given into more than one area at a time, depending on the condition.

While receiving injections for eye muscle conditions, you may need to use eye drops, ointment, a special contact lens, or another device to protect the surface of your eye. Follow your doctor's instructions.

It may take up to 2 weeks after injection before neck muscle spasm symptoms begin to improve. You may notice the greatest improvement after 6 weeks.

If you are being treated for excessive sweating, shave your underarms about 24 hours before your injection. Do not apply antiperspirant or deodorant for 24 hours before or after you receive the injection. Avoid exercise and hot foods or beverages within 30 minutes before the injection.

What happens if I miss a dose?

Since onabotulinumtoxinA (Botox/Botox Cosmetic) has a temporary effect and is given at widely spaced intervals, missing a dose is not likely to be harmful.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Overdose symptoms may not appear right away, but can include muscle weakness, trouble swallowing, and weak or shallow breathing.

Using this medication more often than prescribed will not make it more effective and may result in serious side effects.

What should I avoid after receiving onabotulinumtoxinA?

OnabotulinumtoxinA may cause loss of strength or general muscle weakness, vision problems, or dizziness within hours to weeks of receiving Botox or Botox Cosmetic. If this happens, do not drive a car, operate machinery, or do other dangerous activities.

Avoid going back to your normal physical activities too quickly after receiving an injection.

What other drugs will affect onabotulinumtoxinA?

Tell your doctor about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements. Using onabotulinumtoxinA with certain other medicines may cause serious side effects. Do not start any new medicines until you have told your doctor that you have received onabotulinumtoxinA in the past. Especially tell your doctor if you:

Ask your doctor if you are not sure if your medicine is listed above. Know the medicines you take. Keep a list of your medicines with you to show your doctor and pharmacist each time you get a new medicine. This list is not complete. Other drugs may affect onabotulinumtoxinA, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.


Unopened vials of Botox and Botox Cosmetic should be stored in a refrigerator between 2° to 8°C (36º to 46ºF). Do not use after the expiration date on the vial.

Reconstituted Botox/Botox Cosmetic may be stored in a refrigerator (2° to 8°C) for up to 24 hours until the time of use.


Active ingredient: onabotulinumtoxinA

Inactive ingredients: human albumin and sodium chloride.

Cartons have features to alert users if content may have been compromised, for example, each Botox and Botox Cosmetic vial label and carton labeling also contain the U.S. License number 1889. Do not use the product and contact AbbVie for additional information at 1-800-678-1605 if the labeling is not as described above.

Botox is made from donated human plasma and may contain viruses or other infectious agents. Donated plasma is tested and treated to reduce the risk of contamination, but there is still a small possibility it could transmit disease. Ask your doctor about your risk.


AbbVie Inc.

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Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.