The Flash has no specific weakness like Superman's Kryptonite.
The Flashes (of which there have been four) are still technically human so bullets/weapons andundernourishment/fatigue could effect them the same as they would any human. They have ways of making these problems unlikely, however, such as keeping food storages in their suits and evading bullets and other weaponry using their own speed.
Some villains may also use Flash's speed against him (slippery ice, speed-activated bombs, etc.) or even negate his powers, making him completely human.
Also, The Flash has been known to suffer horrible consequences for going too fast, such as being sent to another timeframe/universe or being sucked into the Speed Force (as occurred in the Crisis On Infinite Earths). However, the speed which is thought of as "too fast" or uncontrollable can vary from comic to comic.
Flash's Weakness Is Gravity
(Justice League s. 2 ep. starcrossed part. 3)
someone
it heats up
Flash's arch enemies is the two zooms
he has had many names but his name at the moment is Barry Allen
ah it flashs even if ya hit a button it doesnt mean dat its on
my car after driving for 15 min traction light flashs
An arc flash or multiple acrs flashs ushally over time rom a damages wire
my air bag light is on, when I start the truck it flashs 6 times then 4 times?
Trying to find if their is a Mythical Creature that is either humanoid or something else that is afraid of flashs of light but is not affected by the sun.
She had a weakness for chocolate.We shall use our enemy's weakness against them.He felt a weakness in the knees.The interviewer asked me what my biggest weakness was.
His weakness was his hair.
Its weakness is gasoline