Botox was approved by the FDA for cosmetic use in 2002, after it was found that the bacterium Clostridium botulinum had various medical and cosmetic applications.
Most notably, Botox's active ingredient temporarily improves the appearance of wrinkles, specifically crow's feet, forehead creases and furrows between the eyebrows.
While it produces varying results in those who have it, most who receive the injection notice a decrease in the amount of wrinkles.
It works by temporarily paralyzing the facial muscle beneath the skin.
It lasts about eight months, and people often choose to get this treatment instead of a more invasive face lift.
But now, doctors are saying that repeated injections of Botox results in diminished results. This is because antibodies are being repeatedly stimulated, leading to the suppression of Botox's efficacy.
In the Journal of Neural Transmission, researchers published an article about a group of 200 Botox users who developed antibodies to the drug, making it less effective as time went on.
It is a similar resistance to the type people develop after repeatedly taking antibiotics.
Researchers warn that having Botox on a steady basis for at least ten years will greatly increase the risk of becoming immune to the drug.
Botox has grown in popularity since it first came out. In 2012, the American Society of Plastic Surgeons reported the highest number of injections at 6.1 million. This is an eight percent increase from 2011. On average, it costs $400 a session.