As with any drug, there are some possible side effects to Botox, the physician-administered injection used to treat fine lines and wrinkles. However, because Botox only stays in the body for a maximum of six months, any side effects associated with the injection will diminish after that time period. People who continue to receive treatments may continue to experience side effects.

Bruising at the site of injection is the most common side effect associated with Botox treatments. Other common side effects include headache, respiratory infections, temporary eyelid droop, nausea and flu-like symptoms.

Botox works by temporarily paralyzing the muscles at the site of injection. In rare cases, this effect may spread to other muscles near the intended area. This can cause temporary paralysis in neighboring muscles, which may lead to eyelid droop or other facial paralysis. This side effect occurs in less than 1 percent of Botox patients.

Other adverse reactions that may be experienced by a minority of Botox patients include pain in the face, erythema (redness of the skin) at the injection site and facial muscle weakness. In most cases, these reactions dissipate roughly one week after injection.

Botox side effects can also occur when the drug interacts with other medications. Before receiving Botox injections, a prospective patient should inform a doctor about any medications she may be taking. Medications that may be dangerous if mixed with Botox include: antibiotics used to treat infections, such as gentamicin, tobramycin, clindamycin and lincomycin; medications used to treat heart rhythm problems, such as quinidine; and medications used to treat other conditions, such as myasthenia gravis, ALS or Alzheimer's disease.

Over-the-counter medications may also interact with the drug formula in Botox. It is wise to discontinue use of over-the-counter medications before and after receiving Botox treatments and inform the plastic surgeon of any drug usage. A pharmacist can also provide complete information about all drugs that may adversely interact with Botox.

Certain groups of people are at greater risk of experiencing Botox side effects. These groups include people with pre-existing infections at the injection site and people with cardiovascular or neuromuscular disorders. Plastic surgeons should always be made aware of any pre-existing conditions before the Botox procedure is performed. It is also crucial for the patient and the physician to be aware of any allergies the patient may have to any drugs that make up the Botox formula. An experienced physician will help determine if Botox is the right treatment for each individual.