Can Botox cause ptosis or permanent muscle paralysis?

Botox generally last 3-6 months, but after long use of Botox some of the underlying muscles may weaken, which results in longer effect.  I doubt your eyelid concerns are from the Botox, but if the concern persists for 2 more months, then you should have an in person evaluation by an experienced Dermatologist, Plastic Surgeon or Ophthalmologist.

Botox results are not permanent, and after many years of doing injections I suggest you speak to someone to evaluate your eyelids.  Best, Dr. Emer.

Botox relaxes the muscles, but the effect is not permanent, and even that you have not had it for the last 7 months, what you may notice is that the frontalis muscle is not as strong as use to be, because the muscle has not regain its full strength. The frontalis muscle is the only muscle that lifts the brows, so to avoid droopiness on the brows, avoid getting Botox in the frontalis muscle, and you can just get it done in the orbicularis oculi and corrugator muscles, that are muscles that pull down the brows, so your brows go up again.