A speed dampening serum is a serum that dampens a speedster's speed, which Harrison Wells developed in his world before crossing over to Earth-1.


Prior to crossing into Earth-1, Harrison Wells made a serum to dampen Zoom's speed.[1]

Wells and Team Flash planned to use it on Zoom using the element of surprise. Their plan however failed after Zoom caught the serum and used it against the Flash. When Zoom took Barry to S.T.A.R. Labs and began draining Barry's speed, he was shot by Cisco Ramon with the serum. Zoom however, removed it and ran away before any harm could be done.[1]

Harry caught Zoom off-guard and stabbed him with a speed-dampening serum, allowing him and Barry to barely get away, Zoom still had enough speed to travel to Earth-One and kill his time remnant.[2]

After Joe shot a B.O.O.T. at Zoom, he proceeded to stab Joe with two doses of speed-dampening serums.[3]


This serum was made specifically to dampen Zoom's speed. Zoom was able to pluck it out after Cisco shot him with it and sped away before he could get captured. However, Cisco later postulates that it doesn't even work on him at all.[4]


The Flash

Season 2

Season 5


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