"Tears Up" pills not working

There is a ceiling value for your base tear rate, but this can be modified by what items you pick up. Eve's Mascara, Polyphemus, The Inner Eye, and Mutant Spider will reduce your tear rate by a given modifier. Your rate of tears is dependent both on your base rate and the modifier.

Also, the tears stat is a bit odd in that maxing it out through normal means will not show up as a maxed stat on the stats screen. The only way to get that max level tears stat is through Soy Milk, but that massive damage reduction doesn't usually make that worth it.

Generally speaking you shouldn't count on the stat screen to be perfectly accurate.

You need to remember that Tear Rate is measured in the delay from one tear fired to the next, increasing the stat decreases this delay.

Tears do not have a maximum value, but there is a so called "soft-cap". After certain set values are reached the benefits gained from this stat start to decrease. This means that after a bunch of Tears Up pills eaten you won't see any improvement.

Your Tear Rate dependes on two factors: Basic Tears Stat and Delay.

• Basic Tears Stat is a stat which affects the final fire rate
• Delay is the number of frames between each shot, and depends on Basic Tears Stat

Since there are 60 frames per second, the final Fire Rate (measured in tears per second) is simply 60 divided by the Delay.
Note, however, that since the Delay has to be a whole number (presumably), the Fire Rate can only be specific numbers.

Note: In the previous Binding of Isaac Tears Rate was "capped" at 6 tears per second, so presumably there's a cap value in the remake, too.

I believe there is a cap on how high your permanent stats can get from pills, but if you are not noticing any change at all, then that is definitely a bug.