What Drugs Should Not Be Taken With Tamsulosin?

If you want to learn what drugs should not be taken with Tamsulosin (Flomax), you’ve come to the right place.

Tamsulosin is an alpha-blocker drug often prescribed for BPH to relax the smooth muscle around the urethra and improve urinary tract symptoms. 

But, just like any other prescription medication, Tamsulosin can interact with other drugs. 

In this article, we will cover what drugs you should not combine with tamsulosin and what else interferes with this drug.

Get Your FREE PSA Lowering Diet Plan!

  • Naturally lower PSA levels
  • Reduce nighttime trips to the bathroom
  • Enjoy better bladder control and urine flow

By clicking “Download Now”, I agree to Ben's Natural Health Terms and Conditions and Privacy Policy.

What drugs should not be taken with tamsulosin?

Before consuming Tamsulosin, you should always consider warnings and interactions with other drugs. 

Talk to your healthcare professional if you are taking or plan to start taking the following drugs:

Type of medicationExamples
Medications that inhibit or block liver enzymesKetoconazole, terbinafine, paroxetine, cimetidine, erythromycin, clarithromycin, duloxetine, paroxetine
Other alpha blockersAlfuzosin, terazosin, doxazosin, prazosin
Medications to treat erectile dysfunctionSildenafil, tadalafil
Antiplatelet medicationsWarfarin

Medications that inhibit or block liver enzymes

The liver metabolizes and eliminates tamsulosin from the blood. That’s why you need a new dose every few hours. 

The elimination rate will be reduced if these medications block your liver enzymes. 

Tamsulosin will build up in your blood, and reach very high doses, increasing the chance of side effects. 

That’s why doctors avoid prescribing some antibiotics, antifungals, sulfa drugs, and other medications that inhibit liver enzymes while taking Tamsulosin.

Other alpha-blockers

In the family of alpha-blockers, we also have terazosin, doxazosin, and alfuzosin. They work similarly and may add up their effects. 

The bad news is that they also work in your blood vessels and may give you severe hypotension, with symptoms such as dizziness and fainting. 

If you are taking hypertension drugs such as metoprolol, talk to your doctor about them to consider a dosage adjustment if needed.

Medications that treat erectile dysfunction

These medications to promote an erection can also relax your arteries and lower your blood pressure. The effect adds up with tamsulosin, which may give you an episode of hypotension. 

You can still use them, but you need a dose adjustment and to follow detailed instructions from your doctor.

Antiplatelet medications

This can be a dangerous interaction because tamsulosin can change your warfarin levels in the blood. 

More warfarin than needed can make your blood more fluid than it should and give you bleeding problems or even precipitate a dangerous hemorrhage. 

If you start taking Flomax (tamsulosin) under warfarin, your healthcare professional will follow up on your warfarin levels to adjust the dose accordingly.

Certain eye surgeries

In addition to the above, your doctor may ask you to discontinue tamsulosin if you’re going to have glaucoma or cataract surgery

This is because eye surgery in patients under tamsulosin can trigger a complication known as intraoperative floppy iris syndrome

This syndrome features swelling of the iris and makes it difficult to continue the procedure.

prostate health supplements

Other interactions that interfere with tamsulosin working

Tamsulosin’s adverse effects and effectiveness depend not only on the drugs you’re taking, it also depends on the pattern you’re following and your lifestyle and habits. 

So, this is a quick checklist you can have around to make sure you’re not interfering with tamsulosin through your lifestyle, habits, foods, and more:

  • Avoid drinking alcohol if you’re on tamsulosin. It can give you hypotension symptoms similar to the ones mentioned above.
  • Take your tamsulosin capsule or pill 30 minutes after the same meal daily to avoid variation in your blood concentration levels.
  • If you’re a grapefruit juice fan, limit your consumption to one or two medium-sized glasses daily.
  • Take the medication regularly, as prescribed by your doctor. Your BPH symptoms may start improving after a few weeks of ongoing use. Do not hesitate to talk to your doctor if something is not going as expected.


Doctors typically prescribe tamsulosin for men in case of prostate enlargement and lower urinary tract symptoms. But it is essential to be aware of what drugs should not be taken with tamsulosin.

The list of medications you should not take with tamsulosin includes drugs that inhibit liver function (ketoconazole, terbinafine, paroxetine, cimetidine), other alpha-blockers (doxazosin, prazosin), erectile dysfunction drugs (sildenafil, tadalafil), and warfarin. 

In the case of ED medications and warfarin, your doctor could decide to make a dose adjustment instead of discontinuing your treatment.

Additionally, for tamsulosin to work as it should, you should adopt a few lifestyle measures, such as avoiding heavy alcohol drinking, not drinking too much grapefruit juice, and taking the medication regularly at the same hour every day.

Explore More

all about prostate health

All About The Prostate: Ben Ong’s Definitive Guide To Prostate Health.


  1. Clincalc DrugStats Database (2023). 
  2. Narayan, P., & Tunuguntla, H. S. G. R. (2005). Long-term efficacy and safety of tamsulosin for benign prostatic hyperplasia. Reviews in Urology7(Suppl 4), S42.
  3. O’Leary, M. P. (2001). Tamsulosin: current clinical experience. Urology58(6), 42-48.

Top Products

Total Health


Glucose Control