 A drooping eyelid can be one of the first signals of a third nerve palsy due to a cerebral aneurysm, that otherwise is asymptomatic and referred to as an oculomotor nerve palsy.Use of high doses of opioid drugs such as morphine, oxycodone, heroin, or hydrocodone can cause ptosis.Pregabalin, an anticonvulsant drug, has also been known to cause mild ptosis.