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As is the case with any other medication, there may be some instances where tamsulosin (Flomax) interactions can occur. In such cases, use is not recommended, or use will have to be adjusted in order to prevent or reduce the risk of negative interactions occurring from other drugs, medical conditions, or even food and drink.

Drug Interactions

According to the FDA, drugs that may interact with this medication include the following:

  • Strong inhibitors of CYP3A4 such as ketoconazole
  • Used with caution in combination with moderate inhibitors of CYP3A4 such as erythromycin, 
  • Used with caution in combination with strong  inhibitors of CYP2D6 such as paroxetine or terbinafine 
  • Concomitant use of PDE5 inhibitors with tamsulosin can potentially cause symptomatic hypotension 

Please note that this list may not be complete, and other interactions with drugs not listed here may occur.

Cialis (Tadalafil)

Tadalafil is a medication provided for erectile dysfunction. Some studies indicate combining these two medications might improve both urine flow and erectile dysfunction. The combination appears to be safe and effective.

Warfarin (Jantovin)

Warfarin is an anticoagulant prescribed to help thin blood. It is unclear if there is an interaction between these two drugs. So far, studies are inconclusive. Anyone taking warfarin should tell their doctor before starting a new medication, including tamsulosin. 

Lisinopril (Qbrelis)

Lisinopril is a medication provided for the treatment of high blood pressure. Taking lisinopril with tamsulosin might increase how fast the high blood pressure medication is excreted

Amoxicillin and Other Antibiotics

Taking amoxicillin and other antibiotics with tamsulosin may slow down the excretion rate of the antibiotic. 

Ibuprofen (Advil)

Taking the analgesic ibuprofen with tamsulosin may slow down the excretion of the tamsulosin, raising the levels in the blood. 

Sildenafil (Viagra)

Taking sildenafil, medication provided for erectile dysfunction with tamsulosin can lead to low blood pressure, dyspepsia, and headache. 

Doxazosin (Cardura)

Doxazosin, a medication for enlarged prostate, with tamsulosin, may increase the risk of certain side effects such as high or low blood pressure. 

Finasteride (Propecia)

Finasteride and tamsulosin are sometimes combined to treat benign prostatic hyperplasia (BPH). 

Oxybutynin (Oxytrol)

Oxybutynin is a medication for the treatment of overactive bladder. When combined with tamsulosin, it can reduce some of the symptoms of urinary tract conditions

Food Interactions

Sometimes the foods we eat and the beverages we drink can also interact with our medications. Food and drink that may interact with this drug include:

  • Taking tamsulosin with any food may decrease its effectiveness by 30 percent, according to the FDA.  (which is why it is recommended to take it 30 minutes after a meal)

Please note that this list may not be complete, and there may be other foods and beverages that interact with this drug.

Tamsulosin and Alcohol

For more information, please visit our page on tamsulosin and alcohol interactions.


It is better not to take tamsulosin at the same time as herbal supplements. 


There are no apparent interactions between vitamins and tamsulosin. 

Disease & Conditions Interactions

Sometimes certain medications can increase the risk of negative side effects for patients with certain diseases or other medical conditions. According to the FDA, diseases, and medical conditions that are known to negatively interact with tamsulosin include:

  • None listed

Please note that this list may not be complete, and there may be other diseases and medical conditions where patients should not take this medication.

Tamsulosin and Pregnancy

For more information, please visit our page on tamsulosin and pregnancy risks.


Some studies indicate patients taking tamsulosin for benign prostate hyperplasia may increase their risk of certain kinds of dementia. 

Sulfa Allergy

Patients with a life-threatening sulfa allergy should use tamsulosin with caution. 

ED (Erectile Dysfunction)

There is some indication that a small number of men taking tamsulosin may experience erectile dysfunction.

Disclaimer: this article does not constitute or replace medical advice. If you have an emergency or a serious medical question, please contact a medical professional or call 911 immediately. To see our full medical disclaimer, visit our Terms of Use page.

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