Parkinson's disease (PD) is a long-term brain disorder that affects movement. Common symptoms include bradykinesia (slow movement), rigidity (stiff muscles), postural instability (balance problems), and a shaking hand. This study looks at using Fexofenadine (an allergy medicine) to help treat PD. People over 50 who are already on dopamine therapy and at certain stages of PD can join. Some people can't join, like those with unusual forms of Parkinson's, women who are pregnant or breastfeeding, and those with certain health problems or allergies. If you want to help test this treatment, you should learn about the time commitment, any possible risks, and if there are any payments.

• The study is for people aged 50 and older with Parkinson's disease.
• Those with unusual Parkinson's forms or certain health issues cannot join.
• Learn about the study length, visits, risks, and compensation before joining.