This article describes possible side effects of Flomax oral capsule. You can explore this overview article to learn more about Flomax, including the drug’s uses, side effects, ways to save on cost, and more.

Flomax is a brand-name medication that comes as a capsule that you swallow. It’s available in a generic version called tamsulosin. This article describes possible side effects of Flomax.

More common side effects of Flomax

Flomax oral capsule may cause mild or serious side effects. Below are some of the more common side effects of this medication.

Commonly reported side effects of Flomax include:

headache
dizziness
stuffy or runny nose
infection, such as the common cold
sexual side effects*

* To learn more about this side effect, see the “Side effects of Flomax in detail” section below.

Mild side effects of Flomax

Flomax may cause certain mild side effects. Usually, mild side effects are temporary and can be easily managed. Tell your doctor or pharmacist if you have side effects that don’t go away or become bothersome.

Mild side effects of Flomax oral capsule that occurred in studies include:

back or chest pain
blurry vision
cough
diarrhea
headache
dizziness
infection, such as the common cold
nausea
sinus congestion
sleepiness or difficulty sleeping (insomnia)
sore throat
stuffy or runny nose
sexual side effects*
weakness or lacking energy
mild allergic reaction*†

* To learn more about this side effect, see the “Side effects of Flomax in detail” section below.
† An allergic reaction is possible with Flomax oral capsule. It wasn’t reported in the drug’s studies, but it has happened since it was approved for use.

Flomax oral capsule may cause more mild side effects than those listed above. For details, see the drug’s prescribing information.

Serious side effects of Flomax

Flomax may cause certain serious side effects. These side effects are usually rare. If you have any serious side effects from Flomax oral capsule, call your doctor right away. But if you think you’re having a medical emergency or your side effects feel life threatening, take immediate action. Call 911 or a local emergency number, or go to the nearest emergency room.

After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. Visit MedWatch’s website if you’d like to notify the FDA about a side effect you’ve had with Flomax.

Serious side effects of Flomax oral capsule that occurred in studies include:

intraoperative floppy iris syndrome (a problem that can occur during certain eye procedures) in people undergoing cataract or glaucoma surgery*
low blood pressure when standing up†
priapism*†
severe allergic reaction†‡

* This side effect wasn’t reported in studies of the drug. But it has occurred in people after the drug was approved for use.
† To learn more about this side effect, see the “Side effects of Flomax in detail” section below.
‡ An allergic reaction is possible with Flomax oral capsule. It wasn’t reported in the drug’s studies, but it has happened since it was approved for use.

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Common questions about side effects of Flomax

Here are answers to some common questions about side effects of Flomax oral capsule. If you have other questions, talk with your doctor or pharmacist.

Is Flomax safe for older adults?

It’s thought so. In studies of Flomax oral capsule, side effects didn’t differ among older adults (age 65 years and above) and younger adults.

Flomax oral capsule is prescribed to treat symptoms of an enlarged prostate, a condition that’s common in men age 50 years and above. But older adults may be more sensitive to some side effects of Flomax, such as dizziness or low blood pressure when standing up.

Talk with your doctor or pharmacist if you’d like to learn more about your risk of side effects from taking Flomax.

How do side effects of Flomax seen in males compare with those seen in females?

Flomax is not approved for use in females.* It’s only approved for use in males* to treat symptoms of an enlarged prostate. Thus, females weren’t included in the drug’s studies.

To learn more about side effects, see the”Side effects of Flomax in detail” section in this article.

* Sex and gender exist on spectrums. In this article, we use the terms “male” and “female” to refer to a person’s sex assigned at birth.

Does Flomax cause long-term side effects?

Yes, in rare cases, Flomax oral capsule may cause long-term side effects. These can last for a while after you’ve stopped taking the drug.

Examples of long-term side effects reported with Flomax oral capsule include:

intraoperative floppy iris syndrome (a problem that can occur during certain eye procedures) in people undergoing cataract or glaucoma surgery. There are reports of this side effect occurring in people who received surgery 9 months after stopping treatment with an alpha-blocker drug. (Flomax is an alpha-blocker drug.)†
priapism; this side effect is a medical emergency that can cause permanent impotence if not treated right away*†

* To learn more about this side effect, see the “Side effects of Flomax in detail” section below.
† This side effect wasn’t reported in studies of the drug. But it has occurred in people after the drug was approved for use.

Talk with your doctor to learn more about these side effects and how to manage them. Ask your doctor for more information about how long these side effects of Flomax may last.

Side effects of Flomax in detail

Below you’ll find details on some of the side effects of Flomax oral capsule.

Sexual side effects

In studies, sexual side effects were a common side effect of Flomax oral capsule. These side effects may be more likely to occur if you take a higher dosage of the drug.

Sexual side effects reported in studies of Flomax include:

Ways to manage

If you experience symptoms of sexual side effects, tell your doctor. Depending on your dosage, they may recommend a lower dose to see if your symptoms go away. Or they may advise switching to a different treatment for an enlarged prostate.

Priapism

In rare cases, Flomax oral capsule may cause priapism. This side effect may be serious. But it’s important to note that priapism wasn’t seen during studies of Flomax. There have been reports of this side effect in people using Flomax oral capsule, but it’s unclear how often this has happened or if Flomax was the cause.

With priapism, you experience a painful, prolonged erection without sexual stimulation. Priapism is considered a medical emergency requiring immediate treatment. Symptoms may include:

an erection lasting longer than 4 hours
pain in the penis

Ways to manage

If you experience symptoms of priapism, call 911 or go to the closest emergency room right away. Priapism is a medical emergency requiring immediate treatment. Permanent impotence can occur without quick treatment.

Your doctor will likely recommend stopping treatment with Flomax should you experience priapism as a side effect.

Low blood pressure when standing up

In studies, low blood pressure when standing or sitting up (orthostatic hypotension) was rare in people taking Flomax oral capsule. This side effect is usually mild but could lead to falls and other serious injuries in rare cases.

With low blood pressure when standing or sitting up, you may experience dizziness and vertigo. This can lead to fainting, resulting in broken bones or other serious injuries.

Ways to manage

If you experience symptoms of low blood pressure when standing or sitting up, tell your doctor. They’ll likely recommend stopping treatment with Flomax. They can discuss other treatments for enlarged prostate that may be safer for you.

Allergic reaction

For some people, Flomax oral capsule can cause an allergic reaction. This side effect wasn’t reported in the drug’s studies, but it has happened since it was approved for use.

Symptoms can be mild or serious, and they may include:

itchiness
skin rash
swelling under the skin, usually affecting eyelids, lips, hands, or feet
swelling of the mouth, tongue, or throat, which can make it hard to breathe
flushing (temporary warmth, redness, or deepening of skin color)

Ways to manage

For mild allergic reaction symptoms, such as a mild rash, call your doctor right away. They may recommend treatments to help manage your symptoms. They’ll also let you know whether you should keep taking the medication.

For severe allergic reaction symptoms, such as swelling or trouble breathing, call 911 or your local emergency number right away. These symptoms require immediate medical care because they can become life threatening. If you’ve had a serious allergic reaction to Flomax, your doctor may recommend taking a different medication instead.

Warnings for Flomax

Below are some factors you may want to discuss with your doctor before taking Flomax.

Warnings

It may not be safe for you to take Flomax oral capsule if you have specific health conditions. These are sometimes called drug-condition interactions. Other things may also affect whether Flomax oral capsule is a safe treatment option for you.

Before taking Flomax oral capsule, tell your doctor about your health and medications you take. Things to consider include:

kidney condition, such as chronic kidney disease
liver condition, such as alcohol-related liver disease
low blood pressure
sulfa allergy
past allergic reaction to Flomax

Flomax and pregnancy

It’s not known whether Flomax oral capsule should be used during pregnancy. The drug was not tested in females* and is only approved for use in males.*

* Sex and gender exist on spectrums. In this article, we use the terms “male” and “female” to refer to a person’s sex assigned at birth.

Flomax and breastfeeding

It’s not known whether Flomax oral capsule should be taken while breastfeeding. The drug was not tested in females* and is only approved for use in males.*

* Sex and gender exist on spectrums. In this article, we use the terms “male” and “female” to refer to a person’s sex assigned at birth.

Flomax and alcohol

Flomax oral capsule is not known to interact with alcohol.

If you have certain side effects, such as dizziness or diarrhea, from Flomax, drinking alcohol could worsen them.

If you drink alcohol, talk with your doctor about whether it’s safe to consume it during your treatment with Flomax oral capsule.

What to ask your doctor

This article describes common and serious side effects of Flomax oral capsule. If your doctor prescribes this medication, they can discuss possible side effects with you. Let your doctor know if you have concerns or questions about treatment with this medication.

Here’s a list of some possible questions you may want to ask your doctor:

How do side effects of Flomax compare to doxazosin?
Are side effects of brand-name Flomax the same as generic tamsulosin?
Can Flomax cause erectile dysfunction as a side effect?
Do I have a higher risk of side effects than others?

Disclaimer: Optum Perks 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.