I need help fixing a poison block. That does damage over time when you touch it. Any Ideas?

I am trying to make a block that will do damage to you over time, but the problem is every time you touch it will speed up the damage. Can someone tell me whats wrong?

function onTouched(part)
	local h = part.Parent:findFirstChild("Humanoid")
	if h~=nil then
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)		
                h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		h.Health = h.Health -2
                wait(1)
		


	end
end

script.Parent.Touched:connect(onTouched)

Okay.... lets start Step 1. Make a brick Step 2. Insert a localscript in that brick or a script... Step 3. Paste this:

----Made by greatneil80----
wait(1) -- wait for the player's service to load
while wait() do -- a loop....
local part = script.Parent -- or the poison brick part :P
local plr = game:GetService("Players").LocalPlayer -- the player
local humanoid = plr.Character.Humanoid -- i'm requesting to get the character ;-;
if humanoid then -- if the humanoid is even a thing then................
	script.Parent.Touched:connect(function() -- if player touches the brick :P
		repeat -- keep repeating until they have one life
			humanoid.Health = Humanoid.Health - 1
			wait(1) -- how long before poison hits the player
		until humanoid.Health == 1
	end) -- add the ends...
end -- change to end) if end doesn't work, it should work though because it ain't a function
end -- change to end if end) doesn't work

Thanks for using, I hope this works :) feel free to accept answer

What you should do, is have a BoolValue in Player module in workspace to tell if it is poisoned or not. I'm gonna pretend it is named Poisoned.

script.Parent.Touched:Connect(function(hit) --:connect is deprecated, you should use :Connect
	if hit.Parent:FindFirstChild('Humanoid') then
		if not hit.Parent.Poisoned.Value then
			hit.Parent.Poisoned.Value = true
			for i = 1, 50 do
				hit.Parent.Humanoid.Health = hit.Parent.Humanoid.Health - 2
				wait(1)
			end
			hit.Parent.Poisoned = false
		end
	end
end)