Modafinil is a Diuretic, it makes you lose water
For most people modafinil presents no serious side effects, and even minor ones are uncommon. However, there is one effect that occurs in the vast majority of people, so much so that it’s not considered a “side effect” but simply a natural part of taking modafinil.
Losing water on modafinil
Modafinil is a diuretic, a compound that causes your body to shed its water weight. Many stimulants have this effect to varying degrees. Other products are made specifically for this purpose, often called “water pills”. You might see these advertised as a way to lose weight quickly, though that is risky and even dangerous behavior.
Modafinil’s Diuretic Effect
Obviously water tends to leave your body in more or less one way: Urination. When you take modafinil, you’ll find that you need to run to the bathroom more frequently than normal. This is a perfectly normal effect, so don’t worry. But you should take some precautions.
How a diuretic works
Your kidneys act as filters for the liquids passing through your body. Whatever doesn’t get absorbed back into the bloodstream gets sent out as urine. Diuretics prevent the kidneys from absorbing sodium, potassium, and sometimes calcium. These three elements are more commonly known as electrolytes, those minerals that sports drinks like Gatorade love to harp on about.
Think about how salt quickly soaks up water. That same process is going on inside your body. If you can’t absorb the salt attached to the water, you’ll need to pass it out. That’s what’s going on when you take modafinil.
Is modafinil bad for your kidneys?
When Provigil was released, the FDA recommended that patients with kidney issues avoid taking it. Your liver does the majority of the processing for modafinil, with only about 10% of it being absorbed in the kidneys. So modafinil shouldn’t cause any damage to your kidneys if they are healthy.
In the kidneys modafinil is turned into modafinil acid as it comes into contact with the electrolytes and water in your kidneys. In people with renal issues this can cause irritation and pain. It also explains why your urine can smell stronger or have a different color when you take modafinil. Interestingly, some ethnicities don’t process this acid as well as others.
Avoid dehydration when you take modafinil
A diuretic can cause you to pass an extra liter of water per day! In response you should increase your water intake. However water alone may not be enough. Keep in mind that you are also losing those electrolytes. A sports drink can replenish those valuable components almost instantly, and so can eating balanced meals.
Going to the bathroom more frequently is a fairly generous offer when you consider modafinil’s potent effects on cognition and concentration.