When you're taking lithium for bipolar disorder, even small changes in your body can push you into dangerous territory. Lithium isn't like most medications. It works in a very narrow range-too little and it doesn't help your mood; too much and it can cause seizures, kidney damage, or even death. The problem isn't just the drug itself. It's what you take with it, what you eat, how much water you drink, and even the weather. This isn't theoretical. People have died from lithium toxicity after taking a common painkiller or starting a water pill without knowing the risk.
Why Lithium Is So Sensitive
Lithium is cleared from your body almost entirely by your kidneys. About 95% of it leaves your system unchanged in your urine. That means anything that affects how well your kidneys work can change your lithium levels fast. Your kidneys don’t just filter blood-they also reabsorb lithium depending on how much salt and water is in your body. If your kidneys slow down, lithium builds up. If you lose fluids, lithium concentrates in your blood. It’s that simple, and that dangerous.Therapeutic levels are between 0.6 and 1.2 mmol/L. Go above 1.5 and you’re in the danger zone. Above 2.0 and you’re at risk of life-threatening toxicity. And it doesn’t take much to cross that line. A single dose of ibuprofen, a few days of not drinking enough water, or even eating less salt can push you over.
NSAIDs: The Silent Threat
Non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen, naproxen, and diclofenac are some of the most common medications people take for headaches, back pain, or arthritis. But for someone on lithium, they’re a red flag. These drugs block enzymes in the kidneys called cyclooxygenases, which help maintain blood flow to the filtering units. When those enzymes are blocked, kidney filtration drops by 25 to 50%. That means lithium isn’t flushed out as quickly-and levels rise.Not all NSAIDs are the same. Indomethacin can spike lithium levels by 30 to 60%. Ibuprofen? Around 25 to 40%. Celecoxib is a bit safer, but still risky, with increases of 15 to 30%. The effect usually shows up within the first week of taking the NSAID. It’s not rare. In fact, studies show NSAID use is one of the top reasons lithium toxicity occurs in older adults.
One fatal case in New Zealand involved a 72-year-old woman on lithium and an ACE inhibitor for blood pressure. She started taking an NSAID for joint pain. Her lithium levels weren’t checked for months. She ended up in the hospital with seizures and died. Her story isn’t unique. Many doctors don’t realize how quickly this interaction can turn deadly-especially in people over 65, who are 3.2 times more likely to experience lithium toxicity.
Diuretics: Water Pills That Can Dry You Out
Diuretics are another major concern. They’re prescribed for high blood pressure, heart failure, or swelling. But they interfere with lithium in two ways: by reducing kidney filtration and by changing how much sodium your body holds.Thiazide diuretics like hydrochlorothiazide are the worst offenders. They can increase lithium levels by 25 to 50% within 7 to 10 days. That’s enough to push someone from a safe level into toxicity. Loop diuretics like furosemide (frusemide) are less risky, but still dangerous-they can raise lithium by 10 to 25%. Even potassium-sparing diuretics like spironolactone have unpredictable effects.
Here’s the twist: some diuretics actually lower lithium levels. Osmotic diuretics like mannitol and carbonic anhydrase inhibitors like acetazolamide increase urine output without reducing kidney filtration. That means lithium gets flushed out faster, which can make your mood unstable. So it’s not just about avoiding diuretics-it’s about knowing which ones are safe and which aren’t.
And don’t forget herbal diuretics. Products marketed as “natural” weight-loss teas or supplements often contain ingredients like dandelion, parsley, or hibiscus. These can cause dangerous lithium spikes through dehydration. People think “natural” means safe. It doesn’t.
Dehydration: The Hidden Trigger
You don’t need to be sick to be at risk. Even mild dehydration-losing just 2 to 3% of your body weight in water-can raise lithium levels by 15 to 25%. That’s the equivalent of skipping water all day after a walk, flying long-haul, or having a stomach bug.When you’re dehydrated, your blood volume drops. Your kidneys respond by holding onto more sodium-and lithium rides along with it. You end up with more lithium in less fluid. That’s why doctors tell people on lithium to drink plenty of water, especially in hot weather, during illness, or after exercise. It’s not a suggestion. It’s a safety rule.
And salt matters too. If you suddenly cut back on salt-maybe you’re trying to eat healthier-your lithium levels can climb. Eating less sodium by 20 to 30 mmol per day can increase lithium concentration by 10 to 20%. On the flip side, eating more salt can lower lithium levels, which might make your mood worsen. Consistency is key. Don’t change your salt intake suddenly. Keep your diet steady.
What to Do If You Need Pain Relief or a Diuretic
Avoiding NSAIDs and diuretics isn’t always possible. Many people need them. The goal isn’t fear-it’s awareness and planning.- If you’re on lithium and need pain relief, talk to your doctor first. Acetaminophen (paracetamol) is usually the safest option. It doesn’t affect kidney filtration the way NSAIDs do.
- If a diuretic is necessary, your doctor might switch you to a loop diuretic like furosemide instead of a thiazide. But even then, you’ll need closer monitoring.
- Never start or stop any medication without telling your prescriber. That includes over-the-counter drugs, supplements, or herbal teas.
When co-use is unavoidable, here’s what works:
- Lower your lithium dose before starting the new drug.
- Check your lithium blood level within 5 to 7 days after starting the new medication.
- Repeat the test weekly for the first month.
- Watch for early signs of toxicity: diarrhea, dizziness, drowsiness, hand tremors, or blurred vision.
Many clinics now use electronic alerts to flag these interactions. But alerts aren’t foolproof. If your doctor didn’t check your lithium level after you started an NSAID, you’re at risk. Be your own advocate.
Who’s at Highest Risk?
Some people are more vulnerable than others:- People over 65-kidney function naturally declines with age.
- Those with kidney disease, heart failure, or diabetes.
- Anyone taking multiple medications that affect the kidneys.
- People who travel frequently or live in hot climates.
- Those who experience vomiting, diarrhea, or fever-any illness that causes fluid loss.
If you fit any of these categories, you need a plan. Ask your doctor for a written guide: what to avoid, when to check levels, what symptoms to watch for, and who to call if something feels off.
What to Do If You Think You’re Toxic
Early signs of lithium toxicity are easy to miss. They feel like the flu, fatigue, or stress:- Diarrhea (68% of early cases)
- Lightheadedness or dizziness (52%)
- Drowsiness or confusion (47%)
- Tremors in your hands
- Blurred vision or ringing in the ears
If you notice these, stop taking any new medications and drink water. But don’t wait. Call your doctor or go to the emergency room. Lithium toxicity can progress quickly. Seizures, coma, and permanent kidney damage are real risks.
There’s no antidote. Treatment is supportive: stopping lithium, IV fluids, and sometimes dialysis. The sooner you act, the better your chances.
Final Thoughts: Stay in Control
Lithium saves lives. But it demands respect. It’s not a medication you can take and forget about. You need to be active in your care. Know your numbers. Know your risks. Know what to avoid.Keep a list of all your medications-prescription, over-the-counter, and supplements. Bring it to every appointment. Tell every new doctor you’re on lithium. Drink water regularly, even if you’re not thirsty. Don’t change your salt intake without talking to your doctor. And if you’re ever unsure, err on the side of caution.
There’s no shame in asking questions. There’s only danger in staying silent.
Can I take ibuprofen if I’m on lithium?
It’s not recommended. Ibuprofen can raise lithium levels by 25-40%, increasing the risk of toxicity, especially in older adults or those with kidney issues. If you need pain relief, acetaminophen (paracetamol) is a safer choice. Always talk to your doctor before taking any NSAID.
How long does it take for NSAIDs to affect lithium levels?
Lithium levels can start rising within 2-3 days of starting an NSAID, with the full effect usually seen within 7-10 days. That’s why doctors recommend checking lithium blood levels within a week of starting a new NSAID and again weekly for the first month.
Do all diuretics raise lithium levels?
No. Thiazide diuretics like hydrochlorothiazide are the most dangerous and can raise lithium by 25-50%. Loop diuretics like furosemide cause smaller increases (10-25%). But osmotic diuretics (like mannitol) and carbonic anhydrase inhibitors (like acetazolamide) actually lower lithium levels, which can make your mood unstable. Always check with your doctor before starting any diuretic.
Can dehydration alone cause lithium toxicity?
Yes. Even mild dehydration-losing just 2-3% of your body weight in water-can increase lithium levels by 15-25%. This can happen during illness, after exercise, during long flights, or in hot weather. Drinking enough water is not optional-it’s part of your treatment plan.
Should I avoid salt if I’m on lithium?
No. Don’t cut back on salt unless your doctor tells you to. Reducing sodium intake can raise lithium levels by 10-20%. Eating too much salt can lower them, which might make your symptoms return. The key is consistency. Keep your salt intake steady-don’t suddenly go low-salt or high-salt.
How often should lithium levels be checked?
If you’re stable, checks every 3-6 months are typical. But if you start a new medication like an NSAID or diuretic, levels should be checked within 5-7 days and then weekly for the first month. After that, your doctor will decide if more frequent checks are needed based on your risk factors.
Are herbal diuretics safe with lithium?
No. Herbal diuretics-like dandelion, parsley, or green tea extracts in weight-loss teas-can cause dangerous lithium spikes through dehydration. They’re not regulated, and their effects aren’t studied in people on lithium. Avoid them entirely unless your doctor approves.
What should I do if I get sick with vomiting or diarrhea?
Stop taking lithium until you’ve spoken to your doctor. Vomiting and diarrhea cause rapid fluid loss, which can spike lithium levels. Drink small sips of water or electrolyte drinks. Don’t wait for symptoms to get worse-call your prescriber right away.
