Lasix, or furosemide, is used to lower blood pressure and reduce swelling and fluid retention caused by certain medical conditions, according to MedlinePlus. Commonly called a "water pill," Lasix causes the kidneys to remove excess water and salt from the body through the urine.
Patients can expect a frequent need to urinate for up to six hours after taking Lasix, states MedlinePlus. This is normal and usually decreases after a few weeks of taking the medication. Taking Lasix causes some users to become sensitive to sunlight, so avoiding prolonged sun exposure and wearing protective clothing and sunscreen is recommended. Individuals who plan on becoming pregnant or are currently pregnant or breastfeeding should notify their doctor before taking Lasix, according to MedlinePlus.
Side effects of Lasix include weakness, muscle cramps, confusion, dizziness, excessive thirst, upset stomach and vomiting. Blurred vision, headache, restlessness and constipation may also result from taking Lasix, according to MedlinePlus. Reporting these side effects to a doctor is recommended only if they are severe or unrelieved. Serious side effects warrant an immediate call to a doctor and include sore throat, fever, ringing in the ears or hearing loss, unusual bruising or bleeding, difficulty breathing or swallowing, severe rash, and rapid, excessive weight loss.