On the subject of whether levodopa helps or hinders constipation the message from the literature is mixed.

According to Poirier et al. [1]:

"Anismus, the abnormal contraction of the external **** sphincter and puborectalis muscle during attempted defecation, is another problem that can occur in synergy with constipation in approximately 65% of PD patients, which is more frequently observed during “off” periods".

[Once again let me report that **** has been generated by the system. It must be a truly scary word.]

On the other hand, the Merck information sheet for Sinemet [2] says that constipation has been reported as an adverse reaction to Sinemet.

As an aside, I used to assume that for something, X, to be described as a "side effect" of a treatment, T, then T had to cause X, or at the very least T had to make X worse. Instead time after time I see many of the less noted symptoms of PD listed as side effects. It's as though causality can no longer be assumed. This is not just a technical point, whether causality is implied affects my decision to take or not to take L/C when I'm constipated.

Reference:

[1] "Gastrointestinal Dysfunctions in Parkinson’s Disease: Symptoms and Treatments"
Andrée-Anne Poirier,1,2 Benoit Aubé,1 Mélissa Côté,1,3 Nicolas Morin,4 Thérèse Di Paolo,1,2 and Denis Soulet
Hindawi Parkinson's Disease 2016
https://www.hindawi.com/journals/pd/2016/6762528/

[2] https://www.merck.com/product/usa/pi...sinemet_pi.pdf

John