During scientific trials, the most frequent side effects after injection of Botox were discovered to be headache, nausea, flu syndrome, respiratory infection, and drooping eyelid. Some less frequent side effects included injection site redness and swelling, facial pain, mild numbness and muscle weakness. Naturally we should expect weakness of muscles that are injected because this is what Botox is meant to do. However, sometimes spread of the toxin can lead to weakness of the neighbouring muscles. Fortunately these adverse events were generally temporary, but there is a chance that they may last longer. |