Whether Methocarbamol can promote hair loss ?

The manufacturer of Methocarbamol does not mention an increased risk of hair loss in patients using this preparation among the side effects.

If you have observed such a relationship in yourself and at the same time eliminated other factors that may affect hair loss, e.g. stress, improper diet, thyroid disorders, it is worth mentioning it to your attending physician at the next visit.

If this symptom is indeed a consequence of using the drug, it may be necessary to change the drug used.

I also encourage you to report this symptom as an adverse reaction.
We wrote more about how to do it and why it is worth submitting a report here:

https://www.gdziepolek.pl/artykuly/jak-i-dlaczego-zglaszac-dzialania-niepozadane

I am sending you materials that may be helpful:

https://www.gdziepolek.pl/kategorie/wypadanie-wlosow