Water Intake While Taking Lithium
Yes, you must maintain adequate fluid intake of 2500-3000 mL daily while taking lithium to prevent toxicity and ensure stable therapeutic levels. 1
Why Adequate Hydration is Critical
Lithium is primarily excreted through the kidneys, and its clearance is directly affected by your body's fluid and sodium balance 1. When you become dehydrated, your kidneys reabsorb more lithium along with sodium, leading to dangerously elevated lithium levels even if you're taking the same dose 2.
The FDA drug label explicitly states that maintaining adequate fluid intake (2500-3000 mL) is essential, particularly during initial stabilization. 1 This is not optional—it's a fundamental safety requirement of lithium therapy.
Specific Hydration Guidelines
Daily Fluid Requirements
- Baseline intake: 2500-3000 mL (approximately 2.5-3 liters) per day during stabilization and maintenance 1
- This should be spread throughout the day, not consumed all at once 3
- Take lithium at the end of a solid meal with at least 250 mL (about 1 cup) of water 4
When to Increase Fluid Intake Further
You need to increase your fluid intake beyond the baseline 2500-3000 mL in these situations:
- During hot weather or heat exposure: Increase by 0.5-1 liter per day to compensate for sweating 5
- With physical exertion or exercise: Up to 3 liters total may be needed 4
- During illness with fever, sweating, vomiting, or diarrhea: Supplemental fluid and salt should be administered 1
- If you develop signs of dehydration: fatigue, decreased urine output, dizziness, or muscle weakness 5
Critical Warning Signs
Dehydration decreases lithium clearance and can rapidly lead to toxicity 2. Watch for these warning signs that require immediate medical attention:
- Diarrhea, vomiting, or excessive sweating 1
- Tremor, drowsiness, confusion, or muscle weakness 1
- Decreased urine output 5
- Dizziness or lightheadedness 5
If any of these occur, contact your physician immediately and consider temporarily stopping lithium until you can be evaluated. 1
Maintain Normal Salt Intake
Equally important: maintain a normal diet including adequate salt (sodium) 1. Low sodium intake causes your kidneys to retain more lithium, increasing toxicity risk 2. Don't restrict salt unless specifically directed by your physician for another medical condition.
Medications That Increase Risk
Certain medications further increase your risk of lithium toxicity by reducing lithium clearance, making adequate hydration even more critical:
- NSAIDs (ibuprofen, naproxen, indomethacin): Can significantly increase lithium levels 1, 6
- Diuretics (especially thiazides): Can increase lithium levels by 25-40% 6
- ACE inhibitors: May impair lithium elimination 6
Avoid NSAIDs whenever possible, and notify your physician before starting any new medication. 3, 7
Monitoring Requirements
Your physician should monitor:
- Lithium levels: Twice weekly during acute phase, then every 6 months once stable 7
- Kidney function (GFR, creatinine): Every 6 months or more frequently if dose changes 7
- Electrolytes: Every 6 months 7
Bottom Line
Adequate hydration (2500-3000 mL daily) is a non-negotiable requirement of safe lithium therapy, not merely a suggestion. Dehydration from any cause—inadequate intake, sweating, illness, or medication interactions—can precipitate lithium toxicity even at previously therapeutic doses. Maintain consistent fluid and salt intake, increase fluids during heat or illness, and seek immediate medical attention if you develop any signs of dehydration or toxicity.