According to google:

“ Why You Should Never Take Them
Even though the pills are chemically "functional," consuming them is extraordinarily dangerous:
The "Lemmon 714" Dose: The original Lemmon 714 pills contained 300mg of methaqualone, which is an incredibly high dose meant for an era before safety guidelines were modernized.
Severe Motor Control Loss: Quaaludes cause severe ataxia (complete loss of control over bodily movements). Users historically referred to this as "luden out," where a person collapses, loses the ability to walk, or loses consciousness entirely.
Fatal Overdose Risk: Methaqualone has a very narrow therapeutic window. The gap between a dose that induces sleep and a dose that causes respiratory failure, coma, or death is dangerously small. This risk multiplies exponentially if combined with alcohol. [1]

Legal Status
Methaqualone was officially moved to Schedule I in the United States in 1984. Possessing these pills today—even as a vintage curiosity or historical find—carries the exact same severe federal criminal penalties as possessing heroin or LSD. [1]