TAMSULOSIN (Flomax): What is used for?

What is tamsulosin?

Tamsulosin (Tamsulosina) is a drug used for the treatment of benign prostatic hyperplasia, kidney stones and overactive bladder. The product ingredient is Tamsulosin hydrochloride (hcl).

The brand name of Tamsulosin in the United States is Flomax.

Mechanism of Action (MOA)

It selectively and competitively binds to post-synaptic alpha1 receptors, in particular to alpha1A and alpha1D subtypes, producing relaxation of the smooth muscle of the prostate and urethra.

Therapeutic Indications, Uses and Benefits of Tamsulosin

Lower urinary tract symptoms associated with benign prostatic hyperplasia.


Oral dose
– Modified or prolonged release capsules: 0.4 mg/day (after breakfast or first meal of the day).
– Prolonged-release tablets: 0.4 mg/day (regardless of meals).

Method of administration

Oral use

Modified-release hard capsule: Administer after breakfast or the first meal of the day.
To be taken whole, with a glass of water while sitting or standing (not lying down).
It should not be broken or chewed.

Prolonged-release tablet: Administer independently of meals.
To be swallowed whole and should not be broken or chewed.


  • Hypersensitivity to Tamsulosin hydrochloride (hcl), including drug-induced angioedema.
  • History of orthostatic hypotension.
  • Severe liver failure.

Warnings and Precautions with Tamsulosin

Severe renal failure.
Periodic control of rectal examination and determination of prostate specific antigen.
Risk of orthostatic hypotension.
Risk of intraoperative flaccid iris syndrome during cataract and glaucoma surgery (interrupt treatment 1-2 weeks prior to surgery).
Do not administer in combination with potent inhibitors of CYP3A4 in patients with slow phenotype metabolizer of CYP2D6.
Warnings and precautions in combination with potent and moderate CYP3A4 inhibitors.
Do not administer in children < 18 years.

Liver failure

Contraindicated in severe liver failure.

Renal Insufficiency

Caution in severe renal failure (lack of studies).

Interactions with Tamsulosin

  • Plasma levels: increased by cimetidine; decreased by furosemide.
  • Elimination speed increased by: diclofenac and warfarin.
  • Risk of hypotension with: other alpha1 adrenergic antagonists.


Not applicable, administered only to male patients.

Effects on driving ability

No studies have been conducted on the ability to drive and use machines. However, in this aspect patients should be aware of the possible presentation of dizziness.

Adverse reactions and side effects of Tamsulosin

Dizziness; alterations in ejaculation, including retrograde ejaculation and ejaculatory insufficiency.


Source: The content of this active ingredient has been written taking into account the clinical and molecular information of all medicines authorised and marketed in the United States under the Unique Ingredient Identifier (UNII) by the Substance Registration System (SRS) of the Food and Drug Administration (FDA) and the United States Pharmacopeia (USP).

In order to know in detail the information authorized by the FDA for each drug, you should consult the corresponding medication guide authorized by the FDA.


PubChem CID: 129211
NCI Thesaurus: C75055

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