6 Tamsulosin Interactions You Should Know About

Many men live with an enlarged prostate, or benign prostatic hyperplasia (BPH). Symptoms such as difficulty urinating and feeling like you’re unable to completely empty your bladder can disrupt your daily routine. Leaking, dribbling, and frequenting the bathroom can also be a problem. When these problems are persistent, they can impact your quality of life.

You may have a prescription for tamsulosin (Flomax) if you’re affected by symptoms like these. It’s an oral prescription medication that works by relaxing muscles in your prostate and bladder. It aims to get these types of symptoms under control.

Tamsulosin is effective for many people, too. But it has some drug and food interactions that can impact your experience with it. Six of the top tamsulosin interactions are highlighted below. 

1. Alcohol

There are risks to drinking alcohol while taking some prescription medications. Tamsulosin is no exception. If you drink alcohol while you’re taking tamsulosin, there’s a chance your blood pressure could drop too low (hypotension). This could place you at an increased risk for falls, which can be dangerous.

The good news is that there isn’t a strong interaction between tamsulosin and alcohol. But taking the two together can still have additive effects on low blood pressure and dizziness. It’s a good idea to take tamsulosin for a few days — without consuming any beer, wine, or liquor — to see how it affects you.

Everyone’s experience with alcohol is different, though. Your healthcare provider can tell you more about the risks of drinking alcohol while taking tamsulosin. They can tell you if occasional alcoholic beverages are OK or if you should steer clear of them altogether.

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2. Medications that block tamsulosin metabolism

After you take a dose of tamsulosin, your liver uses certain enzymes (proteins) to break it down. But other medications you may be taking can alter these enzymes. They make it harder for these enzymes to do their job. This slows down tamsulosin's metabolism, which in turn leads to higher tamsulosin levels in the body and makes tamsulosin side effects more likely to happen.

Many medications, and some foods, block enzymes responsible for breaking down tamsulosin. Common examples include:

• Ketoconazole, a medication used to treat fungal infections

• Terbinafine, another antifungal medication

• Paroxetine (Paxil), a type of selective serotonin reuptake inhibitor (SSRI) antidepressant

• Cimetidine (Tagamet HB), a heartburn medication

• Erythromycin, an antibiotic

• Large amounts of grapefruit juice

Most of these interactions are avoidable. For instance, if you’re taking cimetidine for heartburn, your healthcare provider or pharmacist may recommend a medication like famotidine (Pepcid) as a safer alternative. Many antibiotics, antifungals, and antidepressants are also available that don’t interact with tamsulosin.

This list isn’t exhaustive. Other medications can also affect your liver’s ability to break down tamsulosin. If you’re concerned about an interaction with other medications you’re taking, make sure to talk to your healthcare provider or pharmacist.

3. Some medications used to treat high blood pressure

Tamsulosin is an alpha blocker. Alpha blockers are a class of medications that treat many health conditions, most often high blood pressure and symptoms of an enlarged prostate. Other alpha blockers include doxazosin (Cardura, Cardura XL) and terazosin.

Taking tamsulosin and other alpha blockers together can increase the risk of developing blood pressure that’s too low. Symptoms of low blood pressure include feeling dizzy, lightheaded, or like you’re going to faint. It can also make you feel lightheaded when you go from sitting or lying down to standing. This is known as orthostatic hypotension. Your healthcare provider will likely want you to avoid this interaction altogether.

4. Erectile dysfunction medications like Viagra and Cialis

Phosphodiesterase type 5 (PDE-5) inhibitors are a class of medications that treat erectile dysfunction (ED), among other other health conditions. They include sildenafil (Viagra), tadalafil (Cialis), and others. 

ED medications like sildenafil cause your blood vessels to open up and lower your blood pressure. Taking ED medications and tamsulosin at the same time can also make your blood pressure drop too low.

If you’re taking tamsulosin, your healthcare provider will likely recommend a lower dose of your PDE-5 inhibitor medication. In some cases, they may want you to avoid the combination altogether.

5. Warfarin

Warfarin (Coumadin, Jantoven) is a medication that’s used to treat and prevent blood clots. It’s commonly referred to as a blood thinner, but it doesn’t actually thin the blood. Rather, it slows the formation of blood clots. While normal formation of blood clots is important to stop bleeding, excessive clotting can be harmful.

Tamsulosin may interact with warfarin. But the interaction between them isn’t fully clear. Some small studies have found that tamsulosin may affect warfarin levels, but more data is needed to confirm this interaction.

As a precaution, your healthcare provider may want to monitor your blood work more closely to prevent any side effects while you’re taking this combination.

6. Food effects

Food can positively impact tamsulosin levels in your body. You should take it with food whenever possible. 

If you take tamsulosin on an empty stomach, tamsulosin levels can rise rapidly in your bloodstream. This can lead to more side effects, like headache or dizziness. It’s recommended to take your medication 30 minutes after the same meal each day to maintain consistent tamsulosin levels.

When should I contact my healthcare provider about a tamsulosin interaction?

If you’re concerned about a tamsulosin interaction, don’t hesitate to contact your care team. It helps if you give them an updated list of all medications, vitamins, and supplements you take up front. This helps them screen for interactions and prevent them from happening in the first place.

You should also contact them if you’re experiencing any worrisome side effects while taking tamsulosin. They may or may not be related to an interaction, but it’s important to get them checked out. Your provider can offer tips on how to get your symptoms under control. 

If your symptoms end up being related to an interaction, your healthcare provider may suggest dose adjustments or changing other medications you may be taking. It’s important that you do not make any changes to your medication routine without speaking to your healthcare provider first.

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Written by:

Mandeep Sohal, PharmD

Mandeep Sohal, PharmD, has more than 7 years of experience in the pharmaceutical industry and is licensed in California. In his career, he’s had experience with specialty pharmacy, community pharmacy, pharmacy benefit management, and pharmaceutical manufacturers.

Edited by:

Joshua Murdock, PharmD, BCBBS

Joshua Murdock, PharmD, BCBBS, is a licensed pharmacist in Arizona, Colorado, and Rhode Island. He has worked in the pharmacy industry for more than 10 years and currently serves as a pharmacy editor for GoodRx.

Reviewed by:

Austin Ulrich, PharmD, BCACP

Austin Ulrich, PharmD, BCACP, is a board-certified ambulatory care clinical pharmacist. In his early career, he provided direct patient care in a variety of settings, including hospital and community pharmacies, and in a primary care clinic as a clinical pharmacist.

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