You see these types of hunched over guys in video clips. They're gonna wind up like zombies with whatever drugs come out in the future.

https://www.addictioncenter.com/community/fentanyl-fold/

"What’s The “Fenty Fold” And Why Does It Happen To Fentanyl Users? The “fenty fold” (also “fenty lean” or “fentanyl fold”) is a startling but common occurrence among regular users of fentanyl, and other illicit drugs like xylazine, where they are bent at the waist, slumped forward, in a rigid position. Their heads are bowed, their knees are bent, and they are often unable to respond or move.

While jarring to witness, the fenty fold has become a sad yet common phenomenon in cities like San Francisco and Baltimore, where fentanyl use has grown rampant alongside the growing nationwide trend. Chronic users of fentanyl can be stuck in this position for minutes to hours, with possible complications including decreased breath rate, poor circulation, and increased risk of falls and injuries.

Research has not yet pinpointed what exactly causes the fenty fold, as fentanyl use is not known to directly affect the spine. Instead, it’s becoming clear that it is a neuromuscular side effect of synthetic opioids like fentanyl. Studies from the Journal of Applied Physiology and the Harm Reduction Journal highlighted similar findings that fentanyl use can lead to severe and widespread muscle rigidity, particularly in the trunk muscles, which restricts respiration and affects posture and mobility.

Additionally, doctors and addiction professionals think the fold is also connected to the central nervous depression caused by opioids. After using fentanyl (usually in large amounts), people enter a state of slowed consciousness (nodding out), where their bodies and brains are functioning at a depressed level. This system depression leads to muscle weakness, which causes bending, and slowed thought processing, which inhibits the brain from instructing the body to stand upright, resulting in prolonged time spent in an unnatural position.

While more research is needed on the causes of fentanyl fold, it is clear that it is an uncomfortable and potentially dangerous side-effect of fentanyl use."

I observed this behaviour for over 20 minutes yesterday. Seemed to take effect right after the hit but there were periods of standing up and walking as well, before folding up again.

Would love to know more.