what is the most important information you should know about dysport? spread of toxin effects: in some cases, the effects of dysport and all botulinum toxin products may affect areas of the body away from the injection site. symptoms can happen hours to weeks after injection and may include swallowing and breathing problems, loss of strength and muscle weakness all over the body, double vision, blurred vision and drooping eyelids, hoarseness or change or loss of voice, trouble saying words clearly, or loss of bladder control. swallowing and breathing problems can be life threatening and there have been reports of death. you are at the highest risk if these problems are pre‐existing before injection.