What is a Botox Unit?

We use Unit as a measure of Botox (think, mg of medications or ml of liquid). However, from a scientific point of view, a Unit is defined as, the dose required to be  toxic for 50% of medical mice. This is not meant to scare people, but it was the definition used by these companies and regulating bodies. Also, the injection is made in a different manner in mice and mice obviously need FAR less of the medication to be toxic. 

There are usually 50 or 100 Units in a vial. Think of Botox
Units as grains of salt (or in this case gains of Botox) dissolved in water. The same number of Units can
be put in 1 syringe or many syringes and the same number of Units can be
dissolved in 1 ml or 10 ml of water depending on the concentration desired.

A unit is what is used to measure an amount of Botox before it has been reconstituted. Each vial of Botox Cosmetic normally contains 100 units. 

Dear Aglaet

One unit of BOTOX refers to the biological activity of this medication which is a neuromuscular toxin. The toxin is taken up at the terminus of of the nerve that is responsible for stimulating muscle contraction. The effect of the toxin is the prevention of acetylcholine release at the nerve terminus, preventing muscle contraction. The effect of BOTOX is temporary because the nerve eventually replaces the block terminus.

The definition of a unit the amount of BOTOX that when injected into a 18-20 gram Swiss-Webster female mouse is lethal for 50% of the animals. Currently each lot of BOTOX is tested in this fashion to assure the safety of the product. Animal advocates have challenged Allergan, the maker of BOTOX, to use an assay for the product that does not involve animals dying from respiratory arrest. There is a leg paralysis test that could be used. The difficulty is that as you can imagine, the testing of BOTOX is what ensures the safety of BOTOX. The track record of this product is impeccable. The FDA has approved and vetted the safety of BOTOX based on this testing method. Therefore, changing the testing of the drug would require the approval of the FDA and this is improbable.

Now although one unit of Botox is obviously very dangerous if you are an 18 gram mouse, the amount of BOTOX used for a cosmetic service does not appear to associated with systemic side effect. On the other hand, the FDA is now requiring a new warning for the use of Dysport and BOTOX that these treatments in high enough dose can be assoicated with systemic side effects. The systemic side effects appear to only be associated with the very high doses used to treat medical conditions like cervical dystonia and muscle spasm seen in children with cerebral palsy.

Allergan packages BOTOX in the United States market with 100 units of BOTOX. Dysport is now approved for the United States market. It is also a botulinum toxin A. However it is packaged in vials of 300 and 500 units in the United States. These two drugs are not equivalent. While some claim that BOTOX is approximately 3 times stronger than Dysport, this formula is not precise and it takes clinical experience to determine what is the correct dosage for a give person with any of these products.

Botox has 100 units per vial. The effectiveness of the Botox on diminishing muscle movement is dependent on the dose of units given, not the dilution. Doctors must dilute the bottle of Botox powder with saline to make it a liquid. The doctor then knows, based on the amount of liquid added to the bottle, how many units are contained in a given volume of liquid.

It is the measurement scale and is standardized for Botox made by Allergan.
One bottle has 100 units. Typically we use 20units in the area between eyebrows called Glabella.
Remember the units are different for Dysport the newly approved Botulinum toxin launched by the company Medicis. Their bottle has 300units and typically we inject 50units in the Glabella.
Regards

That is a great question! Here at Beauty Bar Medispa, a unit is 1/100th of the 100 unit vial.  

Thank you for your question. Botox is a purified protein used to address wrinkles associated with facial expression. When injected into the skin Botox will relax the muscles and smoothen out the overlying wrinkles. The most common areas of treatment are in the upper face. These include the horizontal lines seen on the upper forehead when one raises the brows, the vertical lines seen between the brows when one frowns (frown lines), and the crow's feet seen around the eyes when one smiles.Botox comes in a powder in small vials on dry ice or a cold container. Upon receipt from the manufacturer the product is refrigerated or frozen until it is used. Per the manufacturer’s guidelines, Botox is prepared by reconstituting the powder with preservative-free normal saline. I prepare the product using preserved saline which allows for greater comfort during injection and for the product to last longer. The guidelines call for use of 2.5 mL of saline for 100 units on Botox or 1.25 mL of saline for 50 units of Botox, which yields 4 units per 0.1 mL. I use these volumes, but some doctors prefer to use more or less to make the product more dilute or more concentrated. When the product is more dilute, it is easier to use smaller doses which are generally required in the lower face. On the other hand, when the product is more concentrated, it is less likely to spread. Because of variability in preparation, the terms used for dosing are units, not volume. This is because the same number of units can be administered with different volumes of product depending on the preparation. Recommended dosing is given in units, which is a measurement of activity seen in laboratory testing.With any injection, there are risks such as pain, bleeding, bruising, redness, swelling, tenderness, and infection. We take special precautions to minimize these risks such as using a painless technique. We also treat bruises with a laser as early as the next day. Bruises usually resolve within two weeks if untreated. After a laser treatment bruises usually resolve in 1-3 days, but may still take two weeks for full resolution. In addition to these risks, with Botox there is also a risk that the product spreads or diffuses to nearby structures. Spread to nearby muscles can lead to side effects such as the temporary appearance of droopy eyelids or a temporary asymmetric smile.
After a Botox treatment, I recommend that my patients avoid heat exposure, alcohol consumption, and strenuous exercise for 24 hours and not lie down flat for four hours. This is because all of these activities may possibly lead to the movement of the product and consequent side effects such as droopy eyelids. Although there have been no definitive studies shown that these actually occur and some physicians do not provide such aftercare instructions, in the absence of data I err on the side of caution and recommend that my patients avoid such activities.

Please consult with a doctor for specific recommendations. Good luck!

This is an arbitrary number derived from studies in animals. There are 100 units in every Botox vial.  You should ask your doctor to see the bottle (look for the authentic hologram) and ask how fresh the Botox is. Always make sure the price is by the unit, not the cc.

Standard dosing ranges of Botox units to treat certain regions of the face have been published in the medical literature. The measurement of the Botox unit is done in the the manufacturer's (Allergan) lab on each batch of Botox; a unit measures the biologic activity of the Botox so the strength can be kept within a narrow, uniform range.

That is why the FDA recommends that practitioners use Botox Cosmetic purchased from Allergan within the USA. The bottle comes with a hologram for verification of the authenticity of production.