A damning survey by Parkinson's UK found hospital could be "one of the scariest places to be" for people suffering from the an incurable degenerative condition, which affects 10,000 people in Scotland.
The charity said patients are regularly denied their usual medications, with some feeling as though they need to smuggle drugs into hospital.
In one case, sufferer David Allan, 52, from Stirling, was asked to keep his medication in a locked cabinet beside his bed when he was admitted to hospital with a broken hip.
He said: "For the first three days I frequently missed doses because I was so out of it, and couldn't make a fuss.
"Trying to learn to walk again when you've got a replaced hip is one thing, but trying to do it with a bad tremor because you didn't get your medication on time is almost impossible.
"When I insisted on getting my medication on time I got the impression they thought I was asking for special treatment."
To raise awareness of the issue Parkinson's UK commissioned the survey of more than 2000 sufferers, as well as their friends and family.
The poll found 47% said they had been denied regular access to the medication they needed to keep their condition under control while in hospital. Almost 70% said they experienced increased levels of anxiety whilst in hospital because of the difficulties of getting their medication.
The charity said that awareness of the condition among hospital staff remains "woefully inadequate" after the survey found a third of sufferers believed staff had a poor understanding of the importance of giving medication for the condition on time.
"Our research confirms that hospital - where people with Parkinson's should feel safest - can actually be the most dangerous place for them to be," said Katherine Crawford, Scotland Director at Parkinson's UK.
"Being admitted to hospital can be difficult enough, but when that is coupled with the fear and uncertainty of being deprived of your drugs, it can become unbearable.
"Time and again people tell us that they leave hospital with their Parkinson's in a far worse state than when they went in."
She said nurses had told the charity they got just an hour of specialised Parkinson's training.
"This fundamental lack of education has resulted in people with the condition being so terrified by their previous experiences in hospital that they use their wash-bags to smuggle in their medication."
The charity, which released the report to coincide with Parkinson's Awareness Week, said the NHS should allow those with the condition who are able, to take their medication themselves.
The findings come just days after the death of independent MSP and former SNP politician Margo McDonald, 70, who had been suffering from Parkinson's disease.
Parkinson's Awareness Week seeks to expose the realities of life for the 127,000 people living with Parkinson's in the UK.
Parkinson's is a degenerative neurological condition, for which there is currently no cure. The main symptoms of the condition are tremor, slowness of movement and rigidity.
All the figures are from an online survey of more than 3600 individuals with Parkinson's or their family or friends by YouGov in March this year.