Lithium Side Effects: What to Expect and How to Handle Them

If you or someone you know is on lithium for bipolar disorder, you’ve probably heard the drug can cause a lot of weird stuff. That’s true – lithium is powerful, and it can affect many parts of the body. Knowing what to look for can keep you from getting caught off guard.

Common Everyday Symptoms

Most people notice a few mild issues at first. You might feel a little shaky, get a shaky hand, or notice that your hands are trembling a bit. Some report feeling thirsty all the time, and you may find yourself urinating more often. Those changes are usually harmless at low doses, but they’re a sign that your kidneys are working harder.

Weight gain is another frequent complaint. Lithium can make you hold on to water, which adds a few pounds even if you’re not eating more. If you start to feel bloated or notice swelling around your ankles, that’s a red flag. A quick check of your weight each week can help you see if it’s creeping up.

When Things Get Serious

Lithium toxicity is the big worry. It shows up with symptoms like severe nausea, vomiting, and diarrhea. You might feel dizzy, confused, or have trouble walking straight. In extreme cases, it can lead to seizures or even a coma. If you notice any of these signs, call your doctor right away – and don’t wait for the next appointment.

Another serious side effect is thyroid trouble. Lithium can slow down your thyroid, leading to fatigue, cold intolerance, and weight gain that isn’t water‑related. A simple blood test can catch this early, so most doctors check thyroid function every few months.

Kidney health also matters. Long‑term lithium use can reduce kidney function over years. Regular blood tests that measure creatinine and eGFR keep an eye on how well your kidneys are doing. If results start to drift, your doctor might lower the dose or suggest a different medication.

Sometimes, lithium messes with your heart rhythm. You might feel a fast or irregular heartbeat, especially if you’re also taking other meds that affect the heart. An ECG can rule out any dangerous changes, and most patients never have a problem.

Talking to your doctor about side effects isn’t a one‑time thing. Bring a list of every symptom you notice, even the ones that seem minor. Your doctor can adjust the dose, switch to a slow‑release formula, or add a supplement like potassium to balance things out.

Staying on top of your labs is the smartest move. Blood lithium levels should stay between 0.6 and 1.2 mmol/L for most people. Your lab results tell you if you’re in that sweet spot or if you’re edging toward toxicity. Most clinics check these levels after a week of starting a new dose, then every few months after that.

Finally, don’t forget the basics: drink enough water, keep a regular diet, and avoid sudden changes in salt intake. Salt helps your body hold onto lithium, so a sudden low‑salt meal can drop your levels unexpectedly.

Bottom line: lithium can be a game‑changer for mood stability, but it comes with a checklist of side effects. By watching for early signs, staying on schedule with labs, and keeping an open line with your doctor, you can enjoy the benefits while keeping risks low.