Tamsulosin Interactions With Other Drugs- Things You Have To Consider 

So, you or someone you know is dealing with an enlarged prostate – it happens. Tamsulosin, also known as Flomax, is the go-to medicine for this gig. It’s like the muscle relaxer for your prostate and bladder, making life a bit easier. 

This could improve the flow of urine and ease the related symptoms. It’s crucial to understand that tamsulosin doesn’t shrink the prostate size, so over time, the prostate might keep growing, making symptoms worse. While it can help with current problems linked to an enlarged prostate, it might not necessarily prevent the need for surgery down the road.

Now, like any other prescription medicine, tamsulosin can interact with different drugs. If you’re wondering about the Tamsulosin interactions, let’s delve into that.

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Tamsulosin Interactions With Other Drugs

Before consuming tamsulosin, you should always consider what drugs should not be taken with Tamsulosin. If you are thinking about tamsulosin interaction with other drugs, here is the table for you:

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

Liver Enzyme Inhibitors

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.

Alpha Blockers Alert

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.

ED Treatment Dynamics

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 Insights

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.

Eye Surgery Caution

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.

Factors Affecting Tamsulosin Effectiveness

Tamsulosin’s adverse effects and effectiveness depend not only on the drugs you’re taking, it also 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:

Tamsulosin And Alcohol

Avoid drinking alcohol if you’re on tamsulosin. It can give you hypotension symptoms similar to the ones mentioned above. Moreover, consuming alcohol with tamsulosin can amplify the blood pressure-lowering impact, potentially causing dizziness or light-headedness. 

Tamsulosin And Mealtime

Take your tamsulosin capsule or pill 30 minutes after the same meal daily to avoid variation in your blood concentration levels. Ensures your body gets a consistent dose of the medicine, keeping things stable.

Tamsulosin And Grapefruit

If you’re a grapefruit juice fan, limit your consumption to one or two medium-sized glasses daily. If Tamsulosin takes your blood pressure for a dive, you might feel dizzy or faint. To keep things steady, take it slow when getting up or sitting down to avoid any unexpected dips in blood pressure.

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 unexpected.


Doctors typically prescribe tamsulosin for men in case of prostate enlargement and lower urinary tract symptoms. However, it is essential to be aware of tamsulosin interactions with other drugs.

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.

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.

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