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Tamsulosin, a drug in the alpha-blocker class of medications, is used to relieve symptoms of urinary obstruction. It is most commonly prescribed for men who have benign prostatic hyperplasia (BPH). Patients with obstruction of the outlet of their bladders can also benefit from taking this medication. Although this drug is typically well tolerated, side effects can include dizziness, back pain, and sore throat.
The mechanism of action of tamsulosin is to inhibit the alpha-1 adrenergic receptors, which are normally activated by the neurotransmitters epinephrine or norepinephrine. When the alpha-1 adrenergic receptors are activated, they cause blood vessel constriction and muscle contraction. Inhibiting the action of these receptors relaxes these structures. Since tamsulosin works in this way, it is considered to be a member of the drug class called the alpha-blockers.
Tamsulosin is unique among the alpha-blockers because it only affects the alpha-1 adrenergic receptors located in the prostate. Therefore, the medication relaxes the smooth muscle within the prostate, which creates an effective increase in the size of the urethra at this location. Doing this allows urine to flow more freely from the bladder through the urethra, and to the outside the body.
One of the main reasons that people take tamsulosin is for benign prostatic hyperplasia, a condition that causes an enlarged prostate. Often these patients experience symptoms such as straining with urination, weak urinary stream, dribbling of urine, and a sense of incomplete voiding after urination. The medication can decrease many of these symptoms by relieving the obstruction caused by BPH. Another indication for using the medication is to relieve other obstructions of the outlet of the bladder.
Tamsulosin is typically given as a pill that is taken once a day. The medication is often sold under the brand name Flomax®. In the US, it is only available by prescription.
Common side effects of tamsulosin include dizziness, abnormal ejaculation, sore throat, back pain, sleepiness, and cough. Rarely, more severe adverse reactions can develop from using the medication. These can include fainting, low blood pressure, and priapism, which is the medical term for a prolonged penile erection. Some patients are allergic to the medication, and can have reactions including skin rash, shortness of breath, and facial swelling after taking the drug.
Although tamsulosin is typically well tolerated by many patients, certain people should avoid taking the medication. Its use is restricted in patients who are allergic to the medication and in patients who have had cataract surgery in the past. In men suspected to have prostate cancer, the presence of this disease should be evaluated prior to taking the medication.