The patient’s neck stability, posture, torsion, and symmetry should be assessed to determine whether he or she may be at increased risk for adverse events prior to the first injection cycle. A patient with preexisting neck pain and/or weakness may be at higher risk for exacerbation of the condition upon injection of the occipitalis, cervical paraspinal, or trapezius muscle groups. Patients with smaller frames may be at higher risk for neck weakness. Indicated injection sites can still be injected with minimal side effects and unwanted outcomes as long as correct injection sites are targeted and treatments are administered using a superficial approach with avoidance of the mid and lower cervical regions. The cervical paraspinal muscle group is made up of multiple muscles including the trapezius, splenius capitis and cervicis, and semispinalis capitus. This group of muscles helps support the neck, including extension of the head.
Individuals with peripheral motor neuropathic diseases, amyotrophic lateral sclerosis or neuromuscular junction disorders (e. g., myasthenia gravis or Lambert-Eaton syndrome) should be monitored when given botulinum toxin. Patients with neuromuscular disorders may be at increased risk of clinically significant effects including generalized muscle weakness, diplopia, ptosis, dysphonia, dysarthria, severe dysphagia and respiratory compromise from therapeutic doses of BOTOX [see Dysphagia And Breathing Difficulties].
When BOTOX (4, 8, or 16 Units/kg) was administered intramuscularly to pregnant mice or rats two times during the period of organogenesis (on gestation days 5 and 13), reductions in fetal body weight and decreased fetal skeletal ossification were ob served at the two highest doses. The no-effect dose for developmental toxicity in these studies (4 Units/kg) is approximately equal to the human dose of 400 Units, on a body weight basis (Units/kg).
The cosmetic effect of BTX-A on wrinkles was originally documented by a plastic surgeon from Sacramento, California, Richard Clark, and published in the journal Plastic and Reconstructive Surgery in 1989.[51] Canadian husband and wife ophthalmologist and dermatologist physicians, JD and JA Carruthers, were the first to publish a study on BTX-A for the treatment of glabellar frown lines in 1992.[52] Similar effects had reportedly been observed by a number of independent groups (Brin, and the Columbia University group under Monte Keen.[53]) After formal trials, on April 12, 2002, the FDA announced regulatory approval of botulinum toxin type A (Botox Cosmetic) to temporarily improve the appearance of moderate-to-severe frown lines between the eyebrows (glabellar lines).[54] Subsequently, cosmetic use of botulinum toxin type A has become widespread.[78] The results of Botox Cosmetic can last up to four months and may vary with each patient.[79] The US Food and Drug Administration approved an alternative product-safety testing method in response to increasing public concern that LD50 testing was required for each batch sold in the market.[55][56]

Tell your doctor if you have received any other botulinum toxin product in the last 4 months; have received injections of botulinum toxin such as Myobloc®, Dysport®, or Xeomin® in the past (tell your doctor exactly which product you received); have recently received an antibiotic by injection; take muscle relaxants; take an allergy or cold medicine; take a sleep medicine; take aspirin-like products or blood thinners.