Key takeaways

  • Tamsulosin is a generic prescription drug that’s used to treat benign prostatic hyperplasia (BPH). This condition is also known as an enlarged prostate.
  • Tamsulosin can cause side effects ranging from mild issues like headaches and nasal congestion to more serious ones like vision problems and low blood pressure.
  • Sexual side effects, including ejaculation problems, are possible with tamsulosin. Other possible serious side effects of the drug include vision problems and chest pain.

Tamsulosin comes as an oral capsule. It’s also called tamsulosin hydrochloride (HCL). Tamsulosin is available as the brand-name drug Flomax.

This article describes tamsulosin’s side effects. For more information about the drug, see this tamsulosin overview article.

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Some people may experience mild to serious side effects during their tamsulosin treatment. Examples of tamsulosin’s commonly reported side effects include:

To learn more about some of these side effects, see the “Side effects explained” section.

People can respond differently to medications, so these side effects don’t happen to everyone.

Keep reading to learn about other side effects that tamsulosin may cause.

Mild side effects can occur in some people taking tamsulosin. People taking higher doses of tamsulosin had side effects more often than those taking lower doses.

Examples of mild side effects that have been reported with tamsulosin include:

To learn more about some of these side effects, see the “Side effects explained” section.

In most cases, these side effects should be temporary. And some may be easily managed. But if you have any symptoms that are ongoing or bother you, talk with your doctor or pharmacist. And do not stop taking tamsulosin unless your doctor recommends it.

Tamsulosin may cause mild side effects other than the ones listed here. See the drug’s prescribing information for details.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. Sharing your experience helps make medication safer for everyone by giving doctors and researchers more information about how the drug works in real life. If you develop a side effect during treatment with tamsulosin and want to tell the FDA about it, visit MedWatch or call 800-FDA-1088.

Tamsulosin can cause serious side effects, but most are not common.

Serious side effects that have been reported with tamsulosin include:

  • vision problems
  • sexual side effects, including priapism and ejaculation problems
  • severe cold and flu-like symptoms
  • chest pain
  • orthostatic hypotension (low blood pressure upon standing)

To learn more about some of these side effects, see the “Side effects explained” section.

If you develop serious side effects while taking tamsulosin, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Allergic reaction

For some people, tamsulosin can cause an allergic reaction. In general, symptoms of an allergic reaction can be mild or serious.

What might help

If you have mild symptoms of an allergic reaction, such as a mild rash, call your doctor right away. They may suggest a treatment to manage your symptoms and can determine whether you should continue tamsulosin treatment.

If you have symptoms of a severe allergic reaction, such as swelling or difficulty breathing, call 911 or your local emergency number right away. These symptoms could be life threatening and require immediate medical care.

If your doctor confirms you’ve had a serious allergic reaction to tamsulosin, they may have you switch to a different treatment.

In studies, older adults (ages 65 and older) didn’t experience side effects from tamsulosin more often than younger adults. But some older adults may be more sensitive to treatment.

If you’re an older adult and have side effects that are bothersome, talk with your doctor or pharmacist. They can give you recommendations on how to ease your symptoms.

Get answers to some frequently asked questions about tamsulosin’s side effects.

Can tamsulosin be used in females? If so, what side effects occur in females compared with males?

No, tamsulosin is not approved by the Food and Drug Administration (FDA) for use in females. It’s only approved to treat benign prostatic hyperplasia (BPH) in adult males.

Some studies suggest that tamsulosin may be effective for treating lower urinary tract symptoms (LUTS) in females. Using tamsulosin for this purpose would be considered an off-label use. (With off-label use, a drug is used to treat conditions other than what the FDA has approved it for.)

With LUTS, you may have:

Research suggests that tamsulosin may affect female fertility. But this was only seen in animal studies. To learn more about LUTS, tamsulosin, and the drug’s side effects in females, talk with your doctor.

Note: The use of binary terms such as “male” and “female” in this article reflects the language of the sources we’ve used. Unless otherwise noted, it’s unclear whether the research we reference included participants with expansive gender identities.

Is weight gain a side effect of tamsulosin?

No, tamsulosin is not known to cause weight gain. This was not a reported side effect in studies of the drug.

If you’re concerned about weight gain while taking tamsulosin, talk with your doctor. They can help determine what might be causing it and suggest ways to manage your weight.

Does tamsulosin cause long-term side effects?

It’s possible. Some side effects of tamsulosin can become long term if not treated properly.

For example, tamsulosin may cause priapism (painful, long-lasting erection) in rare cases. If not treated right away, this side effect can result in permanent erectile dysfunction (ED). (ED refers to the inability to have or maintain an erection.) If you develop priapism during tamsulosin treatment, contact your doctor immediately.

In rare cases, tamsulosin may cause intraoperative floppy iris syndrome (IFIS). This is a complication that can occur during surgery for glaucoma or cataracts, which are eye-related conditions. A review of studies suggests that the risk of this side effect could continue long after you stop taking tamsulosin.

If you’re planning to have cataract or glaucoma surgery and have taken tamsulosin, tell your surgeon. They may need to change the procedure to help avoid IFIS.

For more information about possible long-term side effects from taking tamsulosin, talk with your doctor or pharmacist.

Learn more about some of the side effects tamsulosin may cause.

Sexual side effects, including ejaculation problems

Atypical ejaculations and priapism are sexual side effects that may occur when taking tamsulosin.

Atypical ejaculations may include:

In studies, this side effect occurred more often in people taking higher doses of tamsulosin.

Priapism (a painful, long-lasting erection) is a rare side effect of tamsulosin. If not treated right away, it can lead to permanent erectile dysfunction (ED). (ED refers to the inability to have or maintain an erection.)

Symptoms of priapism include:

  • penis pain
  • rigid penis shaft
  • erection lasting for 4 hours or more

What might help

If you develop symptoms of priapism, contact your doctor immediately. This is considered a medical emergency.

If you have atypical ejaculations or are concerned about sexual side effects while taking tamsulosin, talk with your doctor. They’ll likely recommend treatment of BPH with another drug.

Orthostatic hypertension

Tamsulosin can cause orthostatic hypotension, which is a sudden drop in blood pressure when you stand up.

Symptoms of this side effect include:

What might help

To help prevent orthostatic hypotension, slowly change your position. For example, if you’re lying down, try sitting up slowly before standing up.

If you start to feel dizzy, sitting or lying down may help ease your symptoms. But if the symptoms don’t go away, contact your doctor.

While taking tamsulosin, try to avoid other triggers of orthostatic hypotension, such as dehydration or drinking alcohol (if you drink).

Certain other drugs taken together with tamsulosin can increase your risk of orthostatic hypotension. Before starting tamsulosin treatment, discuss any other medications you take with your doctor. They’ll let you know whether taking your other medications with tamsulosin may increase your risk of orthostatic hypotension or other side effects.

For more information about orthostatic hypotension, talk with your doctor.

Blurred vision

In studies of tamsulosin, blurred vision was one of the more commonly reported side effects of the drug. With blurred vision, your sight may be clouded, dim, or hazy. You may feel as though your vision is not sharp or in focus.

Blurred vision can occur in one or both eyes. It may affect parts of your vision or all of it.

What might help

A few steps you can take to protect your vision include:

If your vision becomes blurred while taking tamsulosin, talk with your doctor. They can give you more information about blurred vision and the side effects caused by the drug. If you experience blurred vision that’s bothersome, they may have you switch to a different treatment.

Nasal congestion

In studies of tamsulosin, nasal congestion was a commonly reported side effect. Nasal congestion, also called a stuffy nose, occurred more often with higher doses of the drug.

Symptoms of this side effect include:

  • runny or stuffy nose
  • swollen tissue inside the nose
  • sinus pain

What might help

If you develop nasal congestion, try using a humidifier to moisten the air in your room. This may soothe your nasal passageways. If you have asthma, talk with your doctor before using a humidifier.

Ask your pharmacist about saline sprays for relieving a stuffy nose, some of which are available over the counter. These may help ease nasal congestion, flush out irritants, and soothe dry nasal passageways. Your doctor or pharmacist may have suggestions for other nasal congestion remedies as well.

Tamsulosin may not be right for you if you have certain medical conditions. These are known as drug-condition interactions. Other factors may also affect whether tamsulosin is a good treatment option for you.

Talk with your doctor about your health history before starting tamsulosin. Factors to consider include:

Eye problems: Intraoperative floppy iris syndrome (IFIS) is a rare eye problem associated with tamsulosin that can occur during glaucoma or cataract surgery. If you have glaucoma or cataracts and are planning surgery for either condition, discuss this side effect with your doctor.

Allergic reaction: If you’ve had an allergic reaction to tamsulosin or any of its ingredients, your doctor will likely not prescribe tamsulosin. Ask them what other medications are better options for you.

Sulfa allergy: In rare cases, allergic reaction to tamsulosin has occurred in people who have a sulfa allergy. If you have a sulfa allergy, tell your doctor before starting tamsulosin treatment.

Low blood pressure: Tamsulosin can cause a sudden drop in blood pressure upon standing, which is called orthostatic hypotension. If you have low blood pressure, talk with your doctor before taking tamsulosin. They may monitor your blood pressure more closely or switch you to another medication.

Alcohol and tamsulosin

Drinking alcohol during treatment with tamsulosin can increase the drug’s side effects.

Tamsulosin is part of a group of drugs called alpha-blockers. Medications in this group can cause low blood pressure.

Alcohol may also temporarily lower blood pressure in some people. If you drink alcohol while taking tamsulosin, your risk of low blood pressure, dizziness, and fainting may increase.

If you drink alcohol and you’d like to drink it during your tamsulosin treatment, talk with your doctor. They’ll let you know how much alcohol, if any, is safe for you to consume while taking this drug.

Pregnancy and breastfeeding while taking tamsulosin

Tamsulosin is not approved by the Food and Drug Administration (FDA) for use in females. It’s only approved to treat benign prostatic hyperplasia (BPH) in adult males.

Safety information is not available about the risks of taking tamsulosin during pregnancy. Also, it’s not known whether it’s safe to breastfeed while taking tamsulosin.

If you have more questions about taking tamsulosin while pregnant or breastfeeding, talk with your doctor.

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.