Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
Call emergency services for severe breathing difficulty, inability to swallow saliva, blue or grey lips, collapse, or signs of a serious allergic reaction such as facial swelling with breathing trouble.
Seek urgent medical care if you cannot swallow liquids safely, repeatedly choke, develop marked weakness, or have a rapidly worsening voice or swallowing problem.
Contact your treating team during routine hours if breathiness, coughing with liquids or voice weakness is more severe or lasts longer than they told you to expect.
Also call if there is increasing pain, swelling, fever, persistent swallowing trouble or no noticeable treatment effect.
Every sign above is quoted from the sofidex article on Botulinum toxin injection - larynx. If you are not sure, err upward — it is always reasonable to be checked.