injections of botulinum toxin type a ( btx - a , botox cosmetic , allergan inc , ca , usa ) have become one of the most popular cosmetic procedures worldwide ( pitman 2005 ) . in the us , more than 2.2 million cosmetic injections were reported in 2003 , only a year after it received food and drug administration ( fda ) approval for treatment of glabellar lines ( batra et al 2005 ) . today it is the most common cosmetic procedure performed in the us ( wise and greco 2006 ) . in contrast to other products used for cosmetic procedures , btx - a is minimally invasive , relatively easy and quick to administer , has a relatively immediate and noticeable effect and a quick recovery period , and is often more affordable than other cosmetic treatments ( klein 2004 ) . alternative procedures involve the use of injectable fillers ( eg , silicone , collagen ) , resurfacing techniques ( eg , dermabrasion , chemical peels , laser resurfacing ) , and surgery , which may lead to serious and permanent adverse effects , eg , photosensitivity , scarring , surgical morbidity , and involve a long recovery period ( lemperle et al 2001 ; cather et al 2002 ) . btx - a is a neuromuscular blocking agent that works by producing transient , dose - dependent , focal weakening of the facial muscles involved in expressions that lead to a tired , disapproving or aged look , such as frowning or wrinkling the forehead ( klein 2004 ; carruthers et al 2004 ) . the ideal candidates for btx - a injections are men and women between 40 and 60 years of age whose facial wrinkles are primarily caused by repeated , habitual muscle contraction over time ( allergan pi 2005 ) . despite the manufacturer s labeling for the use of btx - a in adults younger than 65 years of age , there have been anecdotal reports of btx - a use in older patients . however , there is little published information on the efficacy and safety of btx - a for cosmetic reasons in this population . prior to its use for cosmetic reasons , local injections of btx - a were successful in treating other disorders characterized by inappropriate and excessive muscle contraction , such as dystonia , blepharospasm , and spasticity ( cote et al 2005 ) . btx - a is one of eight potent botulinum toxin serotypes produced by the bacteria clostridia botulinum , a gram - positive spore - forming anaerobe . commercially available btx - a is a purified and diluted form of the neurotoxin . following injection into a muscle , btx - a binds to the presynaptic nerve terminal and selectively blocks the release of acetylcholine at the neuromuscular junction , thereby preventing muscle contraction . the effect is temporary and reversible following the sprouting of new axons and development of extrajunctional acetylcholine receptors over time . acetylcholine synthesis and storage are not affected ( frampton and easthope 2003 ; klein 2004 ; allergan pi 2005 ) . btx - a is most effective for wrinkles that form because of muscle contraction , where weakening of the muscle smoothes and flattens the overlying skin . after a btx - a injection , an improvement in appearance occurs within 1 to 14 days , peaks at approximately 4 weeks , and begins wearing off after 1012 weeks ; therefore , a repeat injection approximately every 34 months is necessary to maintain the cosmetic effect of btx - a ( klein 2004 ; allergan pi 2005 ) . btx - a is not effective for facial wrinkles caused by mechanisms other than muscle contraction , such as sun damage , environmental pollutants , or subcutaneous soft tissue atrophy . because btx preparations vary in potency , commercially available botulinum toxins , including botox cosmetic , dysport ( ispen ltd , slough , uk ) , and myobloc ( elan pharmaceuticals , san francisco , ca , usa ) , are not interchangeable . cosmetic uses for botulinum toxin include treating the vertical lines between the eyebrows ( glabellar lines ) and on the bridge of the nose , squint lines or crows feet at the corners of the eyes , forehead horizontal lines , periorbital lines and nasolabial folds around the mouth , and the thick platysmal bands around the neck , also known as  turkey neck  ( blitzer and binder 2002 ; carruthers et al 2004 ; klein 2005 ) . the recommended dose for glabellar lines is 20 units distributed among 5 injection sites ; however , the dosing is often individualized according to the location and size of the muscle as well as the depth of the wrinkle . the btx - a doses used for cosmetic purposes are much lower than those used in therapeutic cases ( allergan pi 2005 ) . it is difficult to tell for sure whether patients over the age of 65 respond differently to btx - a than younger patients ; there have been no studies investigating cosmetic uses of btx - a specifically in the elderly , and there have not been enough elderly patients enrolled in clinical studies to make any meaningful comparisons ( allergan pi 2005 ) . however , since the elderly are more likely to have thinner and less elastic skin , weaker facial muscles , and wrinkles that over time are caused by gravity - induced tissue sagging rather than muscle contraction , the elderly are not expected to respond as well to btx - a treatment ( norman 2003 ; rhodes et al 2003 ) . btx - a may help soften wrinkles that are noticeable even without muscle contraction , but additional resurfacing procedures are often needed to lead to visible differences in the appearance of the wrinkle ( patel et al 2004 ) . treatment of forehead lines , for example , would require injections to the frontalis muscle , which many older people use to raise their eyebrows and eyelids to see . older patients may also have extra skin under the brow ( pseudoptosis ) which could be worsened by btx - a treatment . older patients who receive btx - a for glabellar lines may be more at risk for complications such as eyelid ptosis if they have a reduced or absent orbital septum ( fagien 2003 ; klein 2004 ; carruthers et al 2004 ) . because of their delicate skin , older patients are also more susceptible to bruising from btx - a injections . the risk for bruising is even greater among patients taking medications that inhibit clotting , such as vitamin e , aspirin , nonsteroidal antiinflammatory drugs , and herbal products such as ginseng , ginko biloba , and garlic . many physicians advise avoiding these medications and products 1014 days prior to treatment . a full medication and supplement history this is particularly important for elderly patients , who are more likely to be taking multiple medications or supplements ( rhodes et al 2003 ; klein 2004 ; mclean and le couteur 2004 ) . conservative dosing , injection of low volumes , and proper placement of the injection can reduce the possibility of spread of the toxin to unintended muscles . electromyographic guidance may be helpful in selecting the appropriate muscles for injection ( klein 2004 ; carruthers et al 2004 ; vartanian and dayan 2005 ) . the manufacturer recommends starting at the lowest possible effective dose for elderly patients ( allergan pi 2005 ) . the most common side effects are related to the injection technique and include local redness , bruising , swelling , and mild pain ( allergan pi 2005 ) . patients who have severe wrinkles ( which require a higher dose of btx - a ) or who have altered facial anatomy , and those with pre - existing neuromuscular disease are more at risk for complications . other side effects include eyelid ptosis , focal facial weakness , and headache . serious adverse events included dysphagia , flu - like symptoms , and hypersensitivity reactions . complications that result from weakened muscles adjacent to the injection site are due to the diffusion of toxin to unintended muscles ; this may be minimized through proper injection technique ( klein 2004 ; naumann and jankovic 2004 ; batra et al 2005 ; vartanian and dayan 2005 ) . topical anesthetics applied prior to injection , use of smaller gauge needles , slow injection , small doses , and application of ice immediately after injection can help minimize pain and discomfort following btx - a injections . many physicians encourage patients to remain upright for 34 hours after the procedure , avoid massaging the treatment area , and actively contract the injected muscle to encourage the uptake of toxin by the intended muscles ( carruthers and carruthers 1998 ; carruthers et al 2004 ; klein 2004 ) . proper dilution , storage , and handling of btx - a are also essential for minimizing adverse outcomes ( cote et al 2005 ) . btx - a should not be used in patients who are pregnant , nursing , or have neuromuscular disease . patients taking medications that could potentiate the effects of btx - a should also not receive btx - a . btx - a is also contraindicated in the presence of infection or inflammation at the injection site and in patients with known hypersensitivity to btx - a or any ingredient in the formulation ( allergan pi 2005 ) . reports of serious cardiovascular events , including arrhythmias , have been reported in post - marketing surveillance of adverse events related to the cosmetic uses of btx - a . the incidence was 2.8% ( 1/36 ) for serious arrhythmia and 5.6% ( 2/36 ) for any serious cardiovascular event . in many of these cases the patients had preexisting cardiovascular risk factors that may have been related to the adverse event . nevertheless , btx - a should be used with caution in patients with cardiovascular comorbidities , which are more common among the elderly ( wenge 2000 ; cote et al 2005 ) . physicians should consider the suitability of btx - a for elderly patients , taking into account the etiology of their wrinkles , skin fragility , facial anatomy , concomitant medications and medical conditions , risk of adverse effects and the likelihood of treatment benefit . although btx - a has a low perceived risk of side effects , older patients may be more susceptible to these effects . the benefit from btx - a treatment is also questionable since wrinkles in older people are more likely to be caused by factors other than repeated muscle contraction . precautions such as a obtaining a full medication and medical history , beginning with low doses , and proper injection technique are especially important for optimal outcomes in elderly patients who are deemed to be good candidates for btx - a cosmetic injections .
botulinum toxin type a injections are one of the most popular cosmetic procedures for diminishing the appearance of facial lines caused by habitual facial muscle contractions . 
 although the manufacturer s labeling recommends botulinum toxin only for the treatment of glabellar lines among adults younger than 65 years of age , there is widespread use of the toxin for other cosmetic purposes and for patients who may be older than 65 . 
 evidence - based safety and efficacy data on botulinum toxin use in elderly patients is limited . 
 however , given the age - related skin changes and multifactorial causes of wrinkles in the elderly , as well as the higher risk for potential side effects due to concomitant diseases and medications , a careful risk - benefit assessment should precede the decision to use botulinum toxin in the elderly patient .