Botox may cause adverse reactions. These adverse reactions may be local or systemic. The most common adverse reactions are local and include tenderness, bruising, redness, and edema at the site of injection. Local symptoms are usually mild and resolve quickly. However, adverse reactions to Botox injections have been reported to last for several months. Side effects are thought to be rare when the injections are administered by a qualified and experienced physician.
Botox injections may have adverse effects on many systems of the body. For example, side effects may affect the gastrointestinal tract, cardiovascular system, respiratory tract, nervous system, musculoskeletal system, ocular structures, and derma (skin). Adverse reactions may also be due to hypersensitivity.
Gastrointestinal reactions to Botox injections include nausea and dyspepsia indigestion).When injected into the neck muscles, Botox may cause difficulty swallowing (dysphagia).Adverse reactions affecting the cardiovascular system include arrhythmia (irregular heart rhythm), myocardial infarction (commonly referred to as a heart attack), and hypertension (high blood pressure).
Respiratory side effects include respiratory infection, cough, rhinitis, laryngitis, sinusitis, sinus infection, bronchitis, dyspnea (shortness of breath), and flu-like symptoms. Adverse reactions affecting the nervous system include dizziness and drowsiness, numbness, parasthesia (a feeling of pins and needles), anxiety, syncope (loss of consciousness or fainting), focal facial paralysis, and twitch.
Musculoskeletal side effects of Botox include neck pain, back pain, muscle weakness, and hypertonia (abnormally high muscle tension and tightness).
Side effects affecting the ocular structures include drooping of the eyelids, a condition called blepharoptosis or ptosis. Ptosis may last up to 3 weeks after the injection or injections. This reaction is associated with the spread of Botox from the injection site. If drooping eyelids occur, it is usually because the patient rubbed his or her face after treatment. The patient is advised to avoid this action for 12 hours after treatment. Other possible side effects include diplopia (double vision) and photophobia (extreme sensitivity to light).
Dermatologic side effects (those affecting the skin) include rash, irritation, ecchymosis (a discoloration of the skin that occurs as a result of the rupture of underlying blood vessels), and erythema (redness of the skin resulting from the congestion of underlying blood vessels).
Side effects resulting from hypersensitivity include anaphylaxis, dyspnea, and edema of the soft tissues.
Serious, life-threatening, and lethal reactions to Botox have been reported, but they are rare. Life-threatening reactions may affect any number of the body’s systems. Severe reactions to Botox seem to be caused by the migration of the drug from the site of injection. These adverse reactions mimic botulism poisoning. Patients with neuromuscular disorders or motor neuron diseases are at increased risk for systemic adverse reactions to Botox. Individuals with these disorders are more likely to experience dysphagia or respiratory compromise after the administration of Botox than are individuals from the general population. If the patient develops signs of anaphylaxis, uticaria (hives), soft tissue edema, or dyspnea, treatment should immediately be discontinued and appropriate medical intervention taken. Although individuals in some groups seem to be at higher risk for adverse reactions to Botox than individuals in other populations, deaths have occurred after the administration of Botox for a range of disorders and in a range of doses.