Flomax

( Tamsulosin )

Medically Reviewed by Harshi Dhingra, M.D.

Last Reviewed: Jun 27, 2022

Warnings

What are the risks of taking Flomax (tamsulosin)?

Flomax can cause serious health problems, especially in certain high-risk patients.

Orthostasis: This is a sudden drop in blood pressure when you stand up from a sitting or lying position. It is more common at the start of Flomax treatment or after a dose increase. The risk is higher in people who are on medications to control high blood pressure. To help avoid this, do not get up too quickly from lying or sitting. Instead, arise slowly from the bed and keep your feet on the ground for a few minutes before standing up.
Priapism: This is a painful and prolonged erection that lasts for more than 4 hours. If this occurs, get proper medical care emergently to prevent permanent damage to the penis.
Sexual problems: Flomax can cause sexual problems such as low sex drive or ejaculation problems. Talk to your doctor if these side effects are severe or do not improve over time.
Prostate cancer screening: Your doctor may screen you for prostate cancer before starting treatment with tamsulosin to ensure that your enlarged prostate is non-cancerous.
Interactions with other drugs: Flomax can interact with other medicines. Give your doctor a complete list of your medications, including over-the-counter supplements.

What should I tell my doctor before starting Flomax (tamsulosin)?

Tell your doctor if you have ever had an allergic reaction to tamsulosin, sulfa drugs, or other medications. Your pharmacy can give you a list of active and inactive ingredients in Flomax.

Tell your healthcare provider about all your medical conditions. Flomax may not be suitable for people with certain medical conditions, such as liver disease, kidney disease, or prostate cancer.

Be sure to give your doctor a complete list of medications, including prescription drugs, over-the-counter medications, nutritional supplements, vitamins, and herbal products. This can help avoid serious drug interactions.

Flomax is only approved for use in men. Women should not take Flomax, especially if they are pregnant or breastfeeding. If a pregnant woman takes Flomax, she should call her doctor.

What precautions should I take while on Flomax (tamsulosin)?

Keep all appointments with your doctor while on Flomax. Your doctor may start you on a low dose of the medication and increase the dose based on your response. They may also order lab work.

Flomax can make you drowsy or dizzy. Do not drive, operate heavy machinery, or do anything that requires your full attention before knowing how this medicine affects you. You should avoid standing for long or becoming overheated while exercising in hot weather. Remember, drinking alcohol can make drowsiness from prescription medications worse.

Tell your healthcare providers you are on Flomax before undergoing any surgery. Be sure to tell your eye surgeon you are on Flomax before undergoing an eye surgery such as cataract surgery. Also, tell your dentist you are on Flomax before undergoing dental surgery.

What are Flomax (tamsulosin) interactions?

Taking Flomax with some other medications can affect how the medication works. Drug interactions can also increase the risk of serious side effects. Your physician may choose a different BPH medication for you, change the dose or frequency of one or both medicines, and/or closely monitor you for side effects if there are known interactions between Flomax and your other medications.

Using Flomax with the following medications is not recommended:

Boceprevir

There can also be interactions between Flomax and medications such as:

Other alpha-blockers like alfuzosin (Uroxatral), terazosin (Hytrin), prazosin (Minipress), and doxazosin (Cardura).
Anticoagulants or blood thinners like warfarin (Coumadin)
Cimetidine (Tagamet)
Medications for erectile dysfunction (ED) such as sildenafil (Viagra), tadalafil (Cialis), or vardenafil (Levitra).

This list may not describe all possible Flomax interactions. Give your healthcare provider a complete list of your medications, including prescription and non-prescription drugs, vitamins and dietary supplements, and natural products. Also, tell your health care provider if you smoke, drink alcohol, or use illegal drugs because some of these substances can cause serious health complications when used with prescription drugs.

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