Botox derives from C. botulinum bacteria, which are present in many natural settings, including soil, lakes, forests, and the intestinal tracts of mammals and fish.

Naturally occurring C. botulinum bacteria and spores are generally harmless. Problems only arise when the spores transform and the cell population increases. At a certain point, the bacteria begin producing Botulinum toxin, the deadly neurotoxin responsible for botulism.

Botulinum toxin is extremely dangerous. Some scientists have estimated that 1 gram of a crystalline form of the toxin could kill 1 million people and that a couple of kilograms could kill every human on the planet.

However, when Botox is appropriately used in a therapeutic context, it is safe and has few side effects, the American Osteopathic College of Dermatology report.

Manufacturers make Botox injections with very small doses of Botulinum toxin. The drug can temporarily paralyze muscles, which can benefit people with various muscle or nerve disorders.

Commercial preparations of Botulinum toxin include:

• onabotulinumtoxin A (Botox)
• abobotulinumtoxin A (Dysport)
• incobotulinumtoxin A (Xeomin)
• rimabotulinumtoxin B (Myobloc)
• prabotulinumtoxin A (Jeuveau)

People casually use the term “Botox” to describe all of these products, though Botox is a registered trademark that one company owns.

Botox is a neurotoxin. These substances target the nervous system, disrupting the nerve signaling processes that stimulate muscle contraction. This is how the drug causes temporary muscle paralysis.

In order for any muscle to contract, the nerves release a chemical messenger called acetylcholine at the junction where nerve endings meet muscle cells. Acetylcholine attaches to receptors on the muscle cells and causes the cells to contract, or shorten.

Botox injections prevent the release of acetylcholine, which stops the muscle cells from contracting. In this way, the toxin helps the muscles to become less stiff.

The primary use of Botox is reducing the appearance of facial wrinkles.

According to the American Board of Cosmetic Surgery, Botox injections are the most popular cosmetic procedure nationwide. In 2016, over 7 million people had Botox treatments.

The effects are temporary, lasting 3–12 months, depending on the type of treatment.

People often request the injections in the following areas of the face:

• wrinkles between the eyebrows, called frown lines, glabellar lines, or elevens
• wrinkles around the eyes, known as crow’s feet
• horizontal creases in the forehead
• lines at the corners of the mouth
• “cobblestone” skin on the chin

However, the FDA have only approved the injections for use around the eyes and on the forehead.

Research has not shown whether Botox could improve dark circles under the eyes. Learn more here.

Some people also try Botox to improve the appearance of their hair. There is little evidence that this works, however. Find out more here.

Healthcare professionals also use Botox to treat a variety of medical conditions, most of which affect the neuromuscular system.

The FDA have approved Botox for the following uses. Unless otherwise specified, the approval is for use in people 18 or older:

• upper limb spasticity, in anyone older than 2 years
• crossed eyes, or strabismus, in those older than 12 years
• severe underarm sweating, or hyperhidrosis
• preventing migraine in people whose migraine headaches last at least 4 hours on 15 or more days per month
• reducing symptoms of an overactive bladder due to a neurological condition if anticholinergic medications do not help
• eyelid spasms, or blepharospasm, due to dystonia
• a neurological movement disorder called cervical dystonia that affects the head and causes neck pain

Some people also have Botox injections for off-label, or unapproved, uses, including as treatments for:

• alopecia
• sialorrhea, which involves producing too much saliva
• psoriasis
• dyshidrotic eczema, which affects the palms of the hands and soles of the feet
• anismus, a dysfunction of the anal muscle
• post-herpetic neuralgia
• vulvodynia, pain and discomfort in the vagina without a clear cause
• Raynaud’s disease, which affects circulation
• achalasia, an issue with the throat that makes swallowing difficult

Other conditions

According to a 2017 review of existing evidence, other issues and medical conditions that may benefit from off-label Botox use include:

• facial redness and flushing, including during menopause
• keloids and scars from wound healing
• hidradenitis suppurativa, an inflammatory skin disease
• blistering lesions due to Hailey-Hailey disease, a rare genetic disorder

However, confirming that Botox is safe and effective for off-label uses will require more research. Scientists must also establish the appropriate ways to deliver treatment in each case.

Clinicians use Botulinum toxin by diluting the powder in saline and injecting it directly into neuromuscular tissue.

It takes 24–72 hours for the toxin to take effect. Rarely, it can take as long as 5 days for the full effects to show. They may last 3–12 months, depending on the treatment.

People should avoid using Botox during pregnancy or breastfeeding, or if they have ever had an allergic reaction to the drug or any of its ingredients.

What are the safety concerns about Botox during breastfeeding? Find out here.

The cost of Botox depends on various factors, including:

• whether it is for medical or cosmetic purposes
• who provides the treatment
• where the treatment takes place
• the number of Botox units involved

For cosmetic use, The American Society for Aesthetic Plastic Surgery noted in 2016 that, on average:

• the cost of a Botox treatment for frown lines or crows’ feet was $376
• the procedure lasted 30 minutes
• the improvement appeared in 1–5 days
• repeat treatments were necessary every 4–6 months
• the person could return to work at once

Medicare covers the cost of Botox for medical purposes that doctors deem necessary. However, due to the potentially high cost, it is important to confirm that the treatment is covered before the appointment.

When considering Botox for any reason, it is crucial to make sure that the provider is a qualified professional with the appropriate training.

For people looking to have cosmetic Botox, the American Academy of Facial Esthetics have a locator function that can help.

Anyone who believes that Botox might help with a medical condition should speak with their doctor.

People generally tolerate Botox injections well, and side effects are uncommon.

However, depending on the reason for the injections and the person’s response, Botulinum toxin can cause some unwanted effects, including:

• dry eye, following cosmetic uses
• an upset stomach
• numbness
• mild pain, swelling, or bruising around the injection site
• a headache
• temporary eyelid drooping
• temporary unwanted weakness or paralysis in nearby muscles
• urinary problems after treatment for urinary incontinence
• a worsening of neuromuscular disorders
• spatial disorientation or double vision after treatment for strabismus
• corneal ulceration after treatment for blepharitis
• cardiovascular events, such as arrhythmia and myocardial infarction

People should not use Botox if they have:

• a sensitivity or allergy to it
• an infection at the injection site

Depending on the type of treatment, there are concerns that the effects of Botox may extend beyond the injection site, possibly leading to symptoms such as difficulty breathing.

This is more likely to occur in some individuals than others, and genetic factors may play a role.

Also, some people receiving injections of Botulinum toxin type A develop antibodies to the toxin that make subsequent treatments ineffective.

Botox has cosmetic and medical uses. It can reduce the appearance of wrinkles and help treat certain disorders related to the nervous and muscular systems.

If someone wants to try Botox, it is a good idea to speak to a healthcare provider about the risks, costs, and other considerations.