Why Do I Have to Drink Water While Taking Lithium Carbonate?

Summary: Lithium Carbonate is used primarily to treat Bipolar Disorder. It has a long history of use but you must make sure to drink enough water while you are taking it. The mechanism behind the water loss is explained below, including recommendations on how much water to take a day.

Dear Curtis: My doctor recently started me on Lithium Carbonate. When I got the medication at the pharmacy the leaflet that comes with the drug told me that I should drink plenty of water. It mentioned 8 glasses a day but how much really is 8 glasses. But my biggest question is the reason why I have to drink more water? Is Lithium going to hurt me if I forget to drink enough water? I’m a little concerned.

A couple of things before I get into discussing the mechanism behind why you need to keep up on your fluid consumption while taking Lithium.

First, Lithium is one of the older, more established drugs that we have around and it has a proven track record of helping patients, especially in treating Bipolar Disorder. Furthermore, lithium (various salt forms in additions to lithium carbonate) has a long history of use dating back to ancient Roman and Greek times.

It was some of these experiences, though, that proved Lithium has to be closely monitored. So, you’ll likely discover that since your are being started on Lithium it’s likely that your doctor will order blood levels to be drawn occasionally to make sure you stay within therapeutic, or safe, ranges.

The Need for Water While Taking Lithium

In regards to the 8 glasses of water recommendation, most glasses in America are actually cups. So, 1 cup equals 1 glass. That means they recommend 8 cups of water every day while you are taking lithium.

Personally, I’d recommend more water. I generally recommend you shoot for at least 2500ml of water each day. One cup of water is 240ml. So, at least 10 cups a day. I’d be happier if you got close to 3000ml’s a day. A gallon of water is just under 3800ml’s.

Now, let’s touch on why it’s important to take water with Lithium.

In your kidneys is a hormone called ADH (Anti-Diuretic Hormone). When urine passes through your kidneys ADH acts by reabsorbing some of that water back into your system. Lithium inhibits the action of ADH. In short, when you take Lithium you’re peeing more water out that would normally be reabsorbed back into your body.

Lithium also interacts with sodium ions in your body. I don’t want to get too technical but generally, where sodium goes, water follows. Lithium inhibits reabsorption of sodium ions in the tubes of your kidneys causing water to be eliminated.

It’s also important to think just beyond water consumption and also water loss. For example, Lithium can be dangerous if you are sweating excessively or have diarrhea and are losing a lot of water. Generally, there will be some warning signs like headache, dizziness and nausea. But it’s critical that you not only watch you water consumption, but also loss while taking Lithium.


  1. sheila griffin says:

    this is the best explained answer i have found. thank you. appreciated the clearness.

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