In this drug factsheet:
What side effects are possible with this medication?
Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.
The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.
The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.
Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.
- abnormal ejaculation
- decreased sexual drive or performance
- dizziness or lightheadedness
- itching and hives
- stuffy or runny nose
- trouble sleeping
- unusual weakness
Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.
Check with your doctor as soon as possible if any of the following side effects occur:
- dizziness when rising from a lying or sitting position
- fast, pounding heart beat
- vision changes
Stop taking the medication and seek immediate medical attention if any of the following occur:
- priapism (painful, persistent erection of the penis that is not relieved by sexual activity)
- signs of a serious allergic reaction (e.g., abdominal cramps, difficulty breathing, nausea and vomiting, or swelling of the face and throat)
- signs of a severe skin reaction such as blistering, peeling, a rash covering a large area of the body, a rash that spreads quickly, or a rash combined with fever or discomfort
Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.
Are there any other precautions or warnings for this medication?
Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.
Allergy: Some people who are allergic to sulfonamide antibiotics also experience allergic reactions to tamsulosin. Before you take tamsulosin, inform your doctor about any previous adverse reactions you have had to medications, especially sulfamethoxazole. Contact your doctor at once if you experience signs of an allergic reaction such as skin rash, itching, difficulty breathing, or swelling of the face and throat.
Drowsiness/reduced alertness: Tamsulosin may cause drowsiness or dizziness, affecting your ability to drive or operate machinery. Avoid these and other hazardous tasks until you have determined how this medication affects you.
Eye surgery: People who will be undergoing cataract or glaucoma surgery should tell their doctor that they are taking tamsulosin. Your surgeon may advise you to temporarily stop taking the medication before the surgery.
Liver function: Liver disease or reduced liver function may cause this medication to build up in the body, causing side effects. If you have liver problems, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.
Orthostatic hypotension: People taking tamsulosin may experience orthostatic hypotension, which is low blood pressure upon arising. If you experience dizziness or weakness, sit or lie down until the symptoms have disappeared. Fainting is the most severe symptom of orthostatic hypotension. If you experience fainting, contact your doctor as soon as possible.
Priapism: Tamsulosin may cause priapism, which is a painful and persistent erection of the penis that is unrelieved by sexual activity. This condition can lead to damage to the penis or impotence if it is not treated quickly. If you suspect that you have these symptoms, call your doctor or go to the emergency room as soon as possible.
Prostate cancer: Prostate cancer and BPH cause many of the same symptoms. These two diseases frequently coexist. An evaluation should be done to rule out prostate cancer before tamsulosin therapy is started.
Pregnancy: Tamsulosin is not recommended for women, including pregnant women.
Breast-feeding: Tamsulosin is not recommended for women, including breast-feeding women.
Children: This medication is not recommended for children.
What other drugs could interact with this medication?
There may be an interaction between tamsulosin and any of the following:
- alpha/beta agonists (e.g., epinephrine, norepinephrine)
- alpha agonists (e.g., clonidine, methyldopa)
- other alpha blockers (e.g., alfuzosin, doxazosin, prazosin)
- "azole" antifungals (e.g., fluconazole, itraconazole, ketoconazole)
- barbiturates (e.g., phenobarbital, pentobarbital)
- beta-adrenergic blockers (e.g., atenolol, propranolol, sotalol)
- calcium channel blockers (e.g., amlodipine, diltiazem, nifedipine, verapamil)
- grapefruit juice
- HIV non-nucleoside reverse transcriptase inhibitors (NNRTIs; e.g., delaviridine, efavirenz, etravirine, nevirapine)
- HIV protease inhibitors (e.g., indinavir, lopinavir, nelfinavir, ritonavir)
- macrolide antibiotics (e.g., clarithromycin, erythromycin, telithromycin)
- medications for erectile dysfunction (e.g., sildenafil, tadalafil, vardenafil)
- monoamine oxidase inhibitors (MAOIs; e.g., moclobemide, phenelzine, rasagiline, selegiline, tranylcypromine)
- peginterferon Alfa-2b
- St. John's wort
If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:
- stop taking one of the medications,
- change one of the medications to another,
- change how you are taking one or both of the medications, or
- leave everything as is.
An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.
Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.