Flomax Side Effects

by on January 13, 2012


The side effects of Flomax (Tamsulosin) are generally mild and include drowsiness and dizziness. With small changes to habit, you may be able to manage these side effects and continue taking the medication. Exercise caution when operating vehicles or machinery while taking Flomax if you are still unsure of how the medication will affect you.  In rare cases, the side effects may include fainting or a prolonged, painful erection. The majority of patients tolerate Flomax well without these issues.  If you experience any of these side effects, you should contact your doctor immediately.

Common Flomax Side Effects

The most common Flomax side effects include the following:

  • Headache
  • Light-headedness
  • Weakness
  • Insomnia
  • Cough
  • Diarrhea
  • Back pain
  • Drowsiness
  • Sinus inflammation
  • Stuffy or runny nose
  • Sore throat
  • Infections like the flu or common cold
  • Decrease in sexual ability

These side effects are generally mild. However, if they disrupt your everyday life or become severe, you should contact your healthcare provider to discuss more comfortable treatment options.

Serious Flomax Side Effects

Flomax Side Effects

Some patients may be allergic to Flomax. If you are allergic to other sulfa drugs, alert your doctor as you may be allergic to tamsulosin as well. If you are experiencing an allergic reaction, your side effects will include some or all of the following. If you believe you are having an allergic reaction, contact your doctor immediately.

  • Hives or rash
  • Itching
  • Tightness of the chest
  • Difficulty breathing
  • Swelling of the mouth and throat

Other serious Flomax side effects that patients have encountered include:

  • Irregular heartbeat
  • Fast heartbeat
  • Chest pain
  • Fever
  • Blurred vision
  • Light-headedness
  • Shortness of breath
  • Chills
  • Blistered, swollen, peeling or red skin
  • Persistent sore throat
  • Severe dizziness
  • Fainting
  • Prolonged, painful erection

If you experience any of these serious side effects, you should contact your doctor immediately. If you are experiencing dizziness, light-headedness or disorientation you should not drive or operate any dangerous machinery.

Sexual Side Effects

Approximately 8.4 percent of men on the 0.4 mg dose and 18.1 percent of men on the 0.8 mg dose experienced side effects associated with abnormal ejaculation. These include a decrease in ejaculate, inability to ejaculate and retrograde ejaculation which can be seen in the form of cloudy urine after intercourse. Though these side effects are generally harmless, you can consult your doctor about altering your dosage of medication if desired.


Flomax has not been thoroughly studied in relation to pregnancy. This medication is considered to be a pregnancy Category B drug. It is most likely safe for use by pregnant women. However, patients who are pregnant or plan to become pregnant should discuss the benefits and risks with their doctor.

Drowsiness or Dizziness

One of the more common side effects of Flomax is drowsiness. You should exercise extreme caution if you plan to drive or operate heavy machinery while taking this medication. You should also consult your doctor if you are taking other medications which cause drowsiness such as allergy or cold products. Talk to your doctor about the safety of consuming alcohol while taking tamsulosin or Flomax as well.

Dizziness is another frequent side effect. If you experience extreme dizziness, you should sit or lay down. You are most likely to feel dizzy when standing from a lying position. Rise from a laying position to a sitting position first and stand slowly to reduce dizziness and disorientation.

Flomax is an effective treatment for the symptoms of BPH. It’s important to remember that this medication does not cure the disease, and symptoms will reappear if you stop taking it. For this reason, its best to consult your doctor about any Flomax side effects you may experience to explore other solutions. Quitting the medication abruptly on your own can be uncomfortable with the return of your BPH symptoms.