Botulinum toxin A is injected just under the surface of the skin in very small doses, which are not toxic to the total organism, using very fine needles. As a rule 10-15 injection groups are made per armpit. The armpits should therefore first be shaved. The pain from the injections can be compared to a mosquito sting. Treatment can be carried out as an out-patient. Normally the patient´s ability to drive and to work is unimpaired.
Usually no side-effects are seen from injections of botulinum toxin A in the armpits. In individual cases injections in other regions of the body may cause temporary side-effects: feeling slightly ill, tiredness and joint ache, skin rashes, dryness of the mouth, mucous membranes and eyes, changes in skin pigmentation. If an injection is unintentionally made in a muscle, the nerve impulses there will also be inhibited, so that the affected muscle can no longer be fully tensed, depending on the amount injected.
In the case of muscle tension, this is a desired effect, however, in untensed muscles it is a side-effect. It can occur in particular after treatment on the palms of the hands and lead to a temporary weakness of the hand muscles (reduced strength e.g. when turning a key or opening screw caps). This weakness will gradually subside within a few weeks. A possible side-effect for patients suffering from frequent headaches is that repeated treatment in the region of the forehead may lead to less frequent headaches or the disappearance of the headaches. Long-term undesirable side-effects are not known for botulinum toxin A to date. No cases of poisoning from inadvertent injections have been observed.