All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Flomax:
Back pain; cough; decreased sexual ability; diarrhea; dizziness; drowsiness; headache; light-headedness; runny or stuffy nose; sinus inflammation; trouble sleeping; weakness.
Seek medical attention right away if any of these SEVERE side effects occur when using Flomax:
Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, throat, or tongue; unusual hoarseness); blurred vision; chest pain; fainting; fast or irregular heartbeat; fever, chills, or persistent sore throat; prolonged, painful erection; red, swollen, blistered, or peeling skin; severe of persistent dizziness or light-headedness; shortness of breath.
This is not a complete list of all side effects that may occur. If you have questions about side effects, contact your health care provider. Call your doctor for medical advice about side effects.
Nervous System Effects
In one case report, seizure frequency increased in a patient with medial temporal lobe seizures following initiation of tamsulosin treatment. Prior to the use of tamsulosin, the patient experienced 3 to 4 seizures per year. In the first 3 months after starting tamsulosin, seizures were appearing twice a month and by the fourth month of treatment the patient had 3 seizures in one day. Following withdrawal of tamsulosin, seizure frequency returned to baseline.
Nervous system side effects are among the most common and include headache in 4% to 20%, asthenia in 1% to 8%, dizziness in 5% to 15%, somnolence in 0% to 4%, and insomnia in 1% to 2% of patients. (These side effects were also noted among patients treated with placebo in controlled trials, but occurred more often among patients treated with tamsulosin.) According to one case report, tamsulosin caused exacerbation of seizures in a patient with a history of seizures.