What are the side effects of Lasix?
Last updated September 3, 2026.
Peeing more is the job - the NHS common list continues: thirst with dry mouth (dehydration warning), dizziness, headaches, and muscle twitches. The story underneath is salt: furosemide flushes sodium, potassium, and magnesium with the water, and low potassium shows as cramps, weakness, constipation, or irregular heartbeat - hence the periodic blood tests, and often a potassium plan. Habits: dose in the morning (second doses by early afternoon), rise slowly, and weigh yourself regularly - a sudden 2-to-3-pound overnight gain is the early warning your prescriber wants. Call promptly for ringing ears or hearing changes, fainting, or confusion. Pymander is a free AI doctor, 24/7 by text, and can help you track the dose.
What to do
- Morning dosing: keep nights dry.
- Thirst plus dry lips? Hydrate and mention it: dehydration creeps.
- Keep the blood tests: potassium is the watched number.
- Daily weigh-ins if prescribed: sudden gain = call.
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