Lithium levels drop when your kidneys excrete more of the drug, and the most reliable way to speed that process is through hydration and sodium intake. The therapeutic range for lithium sits between 0.5 and 1.2 mmol/L, and toxicity symptoms typically begin when levels climb above 1.5 mmol/L. How you lower your levels depends on how high they are and what pushed them up in the first place.
Why Lithium Levels Rise
Your kidneys handle lithium almost exactly the way they handle sodium. In the kidney’s filtration system, lithium gets reabsorbed alongside sodium in the early part of the tubule. When your body is low on sodium or fluid, your kidneys compensate by pulling more sodium back into the bloodstream, and lithium comes along for the ride. This is the core mechanism behind most cases of elevated lithium levels.
The practical triggers are straightforward: dehydration from vomiting, diarrhea, fever, heavy sweating, or simply not drinking enough water. A low-sodium diet can do it too, because reduced salt intake tells your kidneys to conserve sodium more aggressively, trapping lithium in the process. Even excessive exercise on a hot day can shift the balance enough to matter. The half-life of lithium in a healthy adult averages about 29 hours but can stretch considerably longer when kidney function is compromised, meaning it takes longer for levels to come back down on their own.
Medications That Raise Lithium Levels
Drug interactions are the single most important cause of serious lithium toxicity. Several common medications reduce how efficiently your kidneys clear lithium, sometimes dramatically.
- Thiazide diuretics (often prescribed for blood pressure) are the worst offenders. They cause the kidneys to compensate by reabsorbing more sodium and lithium upstream, typically raising plasma lithium levels by 20% to 40%.
- NSAIDs like ibuprofen and naproxen increase lithium levels. Aspirin is an exception and does not have this effect.
- ACE inhibitors (another common blood pressure medication) carry a significant risk. One population study of adults 66 and older found a 7.6-fold increase in hospitalizations for lithium toxicity within a month of starting an ACE inhibitor.
- Spironolactone, a potassium-sparing diuretic, slightly increases lithium levels by reducing fluid volume.
If your lithium levels recently spiked, check whether you started any new medication or began taking an over-the-counter pain reliever like ibuprofen. Even occasional NSAID use can push levels into a concerning range.
Caffeine’s Surprising Role
Caffeine increases the rate at which your kidneys clear lithium. That’s useful to know, but the real danger runs the other direction: if you suddenly stop drinking coffee or significantly cut back, your lithium levels can rise. Case reports have documented patients developing worse lithium tremor after eliminating caffeine from their diets, with the mechanism being reduced renal lithium clearance. If you’re a regular coffee drinker on lithium, keep your intake roughly consistent rather than quitting abruptly.
What You Can Do at Home
For mildly elevated levels (say, a blood draw that came back a bit above your target range but below 1.5 mmol/L), the strategies are practical and centered on reversing whatever caused the increase.
Stay well hydrated. Water is the baseline, but the sodium connection matters. Your kidneys excrete lithium more effectively when sodium levels are adequate, so maintaining a normal salt intake helps keep lithium from accumulating. This doesn’t mean loading up on salt, but it does mean that crash diets, juice cleanses, or any eating pattern that drastically cuts sodium can backfire. If you’ve been sick with vomiting or diarrhea, replacing both fluids and electrolytes is important.
Review any new medications with your prescriber, including anything you picked up at the pharmacy without a prescription. Stop taking ibuprofen or naproxen if you’ve been using them, and switch to aspirin or acetaminophen for pain relief. Your prescriber may also adjust your lithium dose or temporarily hold it until your levels normalize.
How Elevated Levels Are Treated Medically
When lithium levels climb higher, particularly above 1.5 to 2.0 mmol/L, symptoms like confusion, significant tremor, coordination problems, and muscle twitching often appear. Medical treatment at this stage focuses on intravenous normal saline to restore fluid volume and promote lithium excretion through the kidneys. In one documented case, a patient with lithium overdose received 2 liters of saline quickly followed by a continuous drip, and her levels came down safely without needing more aggressive intervention. This approach works well in people with healthy kidneys and no heart failure.
For acute overdoses of sustained-release lithium tablets, whole bowel irrigation (drinking a large volume of a special solution to flush the gut) can reduce the amount of lithium absorbed into the bloodstream by roughly 67%. This is most effective when started within a few hours of ingestion, and it works specifically because activated charcoal, the standard treatment for many overdoses, does not bind lithium at all.
When Dialysis Becomes Necessary
Hemodialysis is the most effective way to physically remove lithium from the blood, but it’s reserved for severe cases. Expert guidelines from the EXTRIP workgroup recommend dialysis based on a combination of factors: altered mental status, impaired kidney function, and how high the level has climbed. For acute poisoning, dialysis is generally considered when levels reach 4.0 to 5.0 mmol/L. For chronic toxicity, where someone has been accumulating lithium gradually, the threshold is lower, around 2.0 mmol/L, because lithium has had time to distribute into brain and organ tissue where it causes more damage.
One important detail about dialysis: lithium levels often rebound after a session ends because the drug redistributes from tissues back into the blood. Multiple rounds of dialysis are sometimes needed.
Preventing Future Spikes
Most cases of lithium toxicity are preventable. The pattern is almost always the same: something changes in your body’s fluid or sodium balance, or a new medication enters the picture, and lithium quietly accumulates over days to weeks.
Keep your fluid intake consistent, especially in hot weather or during exercise. If you get a stomach bug or any illness that causes fluid loss, treat rehydration as urgent. Maintain a steady, normal-salt diet rather than swinging between high and low sodium intake. Before starting any new prescription or over-the-counter medication, verify it doesn’t interact with lithium. And keep your regular blood monitoring appointments, because catching a slow upward trend in levels is far easier to manage than dealing with full toxicity.