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    HomeMedication GuideTamsulosin safety
    Alpha-1 blocker (BPH)

    Tamsulosin: What to Know Before You Take It

    Also known as Flomax

    A patient-focused safety profile with information from public regulatory sources.

    Reviewed by the OmniRx Health clinical team•Last reviewed Jul 4, 2026

    In plain language

    What Tamsulosin is used for

    1 INDICATIONS AND USAGE Tamsulosin hydrochloride capsules are indicated for the treatment of the signs and symptoms of benign prostatic hyperplasia (BPH) [see Clinical Studies (14)]. Tamsulosin hydrochloride capsules are not indicated for the treatment of hypertension. Tamsulosin hydrochloride capsules are an alpha 1 adrenoceptor antagonist indicated for treatment of the signs and symptoms of benign prostatic hyperplasia (1) Tamsulosin hydrochloride capsules are not indicated for the treatment of hypertension (1)

    Read before you decide

    Risks and precautions

    Risks and warnings

    5 WARNINGS AND PRECAUTIONS Advise patients about the possibility of symptoms related to postural hypotension and to avoid situations where injury could result should syncope occur (5.1) Should not be used in combination with strong inhibitors of CYP3A4. Use with caution in combination with moderate inhibitors of CYP3A4, with strong or moderate inhibitors of CYP2D6, in patients known to be CYP2D6 poor metabolizers, or in combination with other cytochrome P450 inhibitors. (5.2, 7.1, 12.3) Should not be used in combination with other alpha adrenergic blocking agents (5.2, 7.2, 12.3) Exercise caution with concomitant administration of warfarin (5.2, 7.4, 12.3) Advise patients about the possibility and seriousness of priapism (5.3) Intraoperative Floppy Iris Syndrome has been observed during cataract and glaucoma surgery in some patients. Advise patients considering cataract or glaucoma surgery to tell their ophthalmologist that they have taken tamsulosin hydrochloride capsules. (5.5) Advise patients to be screened for the presence of prostate cancer prior to treatment and at regular intervals afterwards (5.4) 5.1 Orthostasis The signs and symptoms of orthostasis (postural hypotension, dizziness, and vertigo) were detected more frequently in tamsulosin hydrochloride capsule-treated patients than in placebo recipients. As with other alpha adrenergic blocking agents there is a potential risk of syncope [see Adverse Reactions (6.1)] . Patients beginning treatment with tamsulosin hydrochloride capsules should be cautioned to avoid situations in which injury could result should syncope occur. 5.2 Drug Interactions Tamsulosin is extensively metabolized, mainly by CYP3A4 and CYP2D6. Tamsulosin hydrochloride capsules 0.4 mg should not be used in combination with strong inhibitors of CYP3A4 (e.g., ketoconazole) [see Drug Interactions (7.1) and Clinical Pharmacology (12.3)] . Tamsulosin hydrochloride capsules should be used with caution in combination with moderate inhibitors of CYP3A4 (e.g., erythromycin), in combination with strong (e.g., paroxetine) or moderate (e.g., terbinafine) inhibitors of CYP2D6, in patients known to be CYP2D6 poor metabolizers particularly at a dose higher than 0.4 mg (e.g., 0.8 mg) [see Drug Interactions (7.1) and Clinical Pharmacology (12.3)]. Tamsulosin hydrochloride capsules should be used with caution in combination with cimetidine, particularly at a dose higher than 0.4 mg (e.g., 0.8 mg) [see Drug Interactions (7.1) and Clinical Pharmacology (12.3)]. Tamsulosin hydrochloride capsules should not be used in combination with other alpha adrenergic blocking agents [see Drug Interactions (7.2) and Clinical Pharmacology (12.3)]. Caution is advised when alpha adrenergic blocking agents including tamsulosin hydrochloride are coadministered with PDE5 inhibitors. Alpha-adrenergic blockers and PDE5 inhibitors are both vasodilators that can lower blood pressure. Concomitant use of these two drug classes can potentially cause symptomatic hypotension [see Drug Interactions (7.3) and Clinical Pharmacology (12.3)]. Caution should be exercised with concomitant administration of warfarin and tamsulosin hydrochloride capsules [see Drug Interactions (7.4) and Clinical Pharmacology (12.3)]. 5.3 Priapism Rarely (probably less than 1 in 50,000 patients), tamsulosin, like other alpha 1 antagonists, has been associated with priapism (persistent painful penile erection unrelated to sexual activity). Because this condition can lead to permanent impotence if not properly treated, patients must be advised about the seriousness of the condition. 5.4 Screening for Prostate Cancer Prostate cancer and BPH frequently coexist; therefore, patients should be screened for the presence of prostate cancer prior to treatment with tamsulosin hydrochloride capsules and at regular intervals afterwards. 5.5 Intraoperative Floppy Iris Syndrome Intraoperative Floppy Iris Syndrome (IFIS) has been observed during cataract and glaucoma surgery in some patients on or previously treated with alpha 1 blockers, including tamsulosin hydrochloride capsules [see Adverse Reactions (6.2)]. Most reports were in patients taking the alpha 1 blocker when IFIS occurred, but in some cases, the alpha 1 blocker had been stopped prior to surgery. In most of these cases, the alpha 1 blocker had been stopped recently prior to surgery (2 to 14 days), but in a few cases, IFIS was reported after the patient had been off the alpha 1 blocker for a longer period (5 weeks to 9 months). IFIS is a variant of small pupil syndrome and is characterized by the combination of a flaccid iris that billows in response to intraoperative irrigation currents, progressive intraoperative miosis despite preoperative dilation with standard mydriatic drugs and potential prolapse of the iris toward the phacoemulsification incisions. The patient's ophthalmologist should be prepared for possible modifications to their surgical technique, such as the utilization of iris hooks, iris dilator rings, or viscoelastic substances. IFIS may increase the risk of eye complications during and after the operation. The benefit of stopping alpha 1 blocker therapy prior to cataract or glaucoma surgery has not been established. The initiation of therapy with tamsulosin in patients for whom cataract or glaucoma surgery is scheduled is not recommended. 5.6 Sulfa Allergy In patients with sulfa allergy, allergic reaction to tamsulosin hydrochloride capsules has been rarely reported. If a patient reports a serious or life-threatening sulfa allergy, caution is warranted when administering tamsulosin hydrochloride capsules.

    Who should not take it

    4 CONTRAINDICATIONS Tamsulosin hydrochloride capsules are contraindicated in patients known to be hypersensitive to tamsulosin hydrochloride or any component of tamsulosin hydrochloride capsules. Reactions have included skin rash, urticaria, pruritus, angioedema, and respiratory symptoms [see Adverse Reactions (6.2)] . Contraindicated in patients known to be hypersensitive to tamsulosin hydrochloride or any component of tamsulosin hydrochloride capsules (4, 6.2)

    Medication review

    Tamsulosin drug interactions

    Tamsulosin + ItraconazoleTable 1:Drug Interactions with Itraconazole that Affect Concomitant Drug Concentrations Examples of Concomitant Drugs Within Class Prevention or Management Drug Interactions with Itraconazole that Increase Concomitant Drug Concentrations and May Increase Risk of Adverse Reactions Associated with the Concomitant Drug Alpha Blockers Alfuzosin Silodosin Tamsulosin Not recommended during and 2 weeks after itraconazole treatment.Major interactionTamsulosin + Ketoconazole7 DRUG INTERACTIONS • Tamsulosin hydrochloride capsules 0.4 mg should not be used with strong inhibitors of CYP3A4 (e.g., ketoconazole).Major interactionTamsulosin + Warfarin(5.2, 7.1, 12.3) Should not be used in combination with other alpha adrenergic blocking agents (5.2, 7.2, 12.3) Exercise caution with concomitant administration of warfarin (5.2, 7.4, 12.3) Advise patients about the possibility and seriousness of priapism (5.3) Intraoperative Floppy Iris Syndrome has been observed during cataract and glaucoma surgery in some patients.Major interactionTamsulosin + Atenolol7.5 Nifedipine, Atenolol, Enalapril Dosage adjustments are not necessary when tamsulosin hydrochloride capsules are administered concomitantly with nifedipine, atenolol, or enalapril [see Clinical Pharmacology (12.3)].Moderate interactionTamsulosin + Digoxin7.6 Digoxin and Theophylline Dosage adjustments are not necessary when a tamsulosin hydrochloride capsules are administered concomitantly with digoxin or theophylline [see Clinical Pharmacology (12.3)].Moderate interactionTamsulosin + Enalapril7.5 Nifedipine, Atenolol, Enalapril Dosage adjustments are not necessary when tamsulosin hydrochloride capsules are administered concomitantly with nifedipine, atenolol, or enalapril [see Clinical Pharmacology (12.3)].Moderate interactionTamsulosin + Nifedipine7.5 Nifedipine, Atenolol, Enalapril Dosage adjustments are not necessary when tamsulosin hydrochloride capsules are administered concomitantly with nifedipine, atenolol, or enalapril [see Clinical Pharmacology (12.3)].Moderate interactionTamsulosin + ParoxetineTamsulosin hydrochloride capsules should be used with caution in combination with moderate inhibitors of CYP3A4 (e.g., erythromycin), in combination with strong (e.g., paroxetine) or moderate (e.g., terbinafine) inhibitors of CYP2D6, or in patients known to be CYP2D6 poor metabolizers, particularly at a dose higher than 0.4 mg (e.g., 0.8 mg).Moderate interactionTamsulosin + Furosemide7.7 Furosemide Tamsulosin hydrochloride capsules had no effect on the pharmacodynamics (excretion of electrolytes) of furosemide.Minor interactionTamsulosin + TadalafilClinical pharmacology studies have been conducted with coadministration of tadalafil with doxazosin, tamsulosin or alfuzosin.Minor interaction
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    FDA safety data

    Most-reported side effects

    Based on 20,450 FAERS reports. Reports do not prove the drug caused the effect.

    fatigue 1,502dyspnoea 1,415dizziness 1,256diarrhoea 1,199off label use 1,029drug ineffective 1,028headache 956fall 905asthenia 891nausea 855cough 772pruritus 712
    Explore full FDA safety data

    Regulatory record

    FDA recalls (2)

    Class IITerminated · Jul 17, 2019

    Failed Dissolution Specifications

    Recalling firm: Macleods Pharma Usa Inc

    Class IITerminated · Feb 22, 2019

    Failed Dissolution Specifications: High Out-of-Specification dissolution results were observed during stability testing.

    Recalling firm: Ascend Laboratories LLC

    Common questions

    Patient questions

    What is Tamsulosin prescribed for?

    1 INDICATIONS AND USAGE Tamsulosin hydrochloride capsules are indicated for the treatment of the signs and symptoms of benign prostatic hyperplasia (BPH) [see Clinical Studies (14)]. Tamsulosin hydrochloride capsules are not indicated for the treatment of hypertension. Tamsulosin hydrochloride capsules are an alpha 1 adrenoceptor antagonist indicated for treatment of the signs and symptoms of benign prostatic hyperplasia (1) Tamsulosin hydrochloride capsules are not indicated for the treatment of hypertension (1)

    What are the key warnings and safety precautions for Tamsulosin?

    5 WARNINGS AND PRECAUTIONS Advise patients about the possibility of symptoms related to postural hypotension and to avoid situations where injury could result should syncope occur (5.1) Should not be used in combination with strong inhibitors of CYP3A4. Use with caution in combination with moderate inhibitors of CYP3A4, with strong or moderate inhibitors of CYP2D6, in patients known to be CYP2D6 poor metabolizers, or in combination with other cytochrome P450 inhibitors. (5.2, 7.1, 12.3) Should not be used in combination with other alpha adrenergic blocking agents (5.2, 7.2, 12.3) Exercise caution with concomitant administration of warfarin (5.2, 7.4, 12.3) Advise patients about the possibility and seriousness of priapism (5.3) Intraoperative Floppy Iris Syndrome has been observed during cataract and glaucoma surgery in some patients. Advise patients considering cataract or glaucoma surgery to tell their ophthalmologist that they have taken tamsulosin hydrochloride capsules. (5.5) Advise patients to be screened for the presence of prostate cancer prior to treatment and at regular intervals afterwards (5.4) 5.1 Orthostasis The signs and symptoms of orthostasis (postural hypotension, dizziness, and vertigo) were detected more frequently in tamsulosin hydrochloride capsule-treated patients than in placebo recipients. As with other alpha adrenergic blocking agents there is a potential risk of syncope [see Adverse Reactions (6.1)] . Patients beginning treatment with tamsulosin hydrochloride capsules should be cautioned to avoid situations in which injury could result should syncope occur. 5.2 Drug Interactions Tamsulosin is extensively metabolized, mainly by CYP3A4 and CYP2D6. Tamsulosin hydrochloride capsules 0.4 mg should not be used in combination with strong inhibitors of CYP3A4 (e.g., ketoconazole) [see Drug Interactions (7.1) and Clinical Pharmacology (12.3)] . Tamsulosin hydrochloride capsules should be used with caution in combination with moderate inhibitors of CYP3A4 (e.g., erythromycin), in combination with strong (e.g., paroxetine) or moderate (e.g., terbinafine) inhibitors of CYP2D6, in patients known to be CYP2D6 poor metabolizers particularly at a dose higher than 0.4 mg (e.g., 0.8 mg) [see Drug Interactions (7.1) and Clinical Pharmacology (12.3)]. Tamsulosin hydrochloride capsules should be used with caution in combination with cimetidine, particularly at a dose higher than 0.4 mg (e.g., 0.8 mg) [see Drug Interactions (7.1) and Clinical Pharmacology (12.3)]. Tamsulosin hydrochloride capsules should not be used in combination with other alpha adrenergic blocking agents [see Drug Interactions (7.2) and Clinical Pharmacology (12.3)]. Caution is advised when alpha adrenergic blocking agents including tamsulosin hydrochloride are coadministered with PDE5 inhibitors. Alpha-adrenergic blockers and PDE5 inhibitors are both vasodilators that can lower blood pressure. Concomitant use of these two drug classes can potentially cause symptomatic hypotension [see Drug Interactions (7.3) and Clinical Pharmacology (12.3)]. Caution should be exercised with concomitant administration of warfarin and tamsulosin hydrochloride capsules [see Drug Interactions (7.4) and Clinical Pharmacology (12.3)]. 5.3 Priapism Rarely (probably less than 1 in 50,000 patients), tamsulosin, like other alpha 1 antagonists, has been associated with priapism (persistent painful penile erection unrelated to sexual activity). Because this condition can lead to permanent impotence if not properly treated, patients must be advised about the seriousness of the condition. 5.4 Screening for Prostate Cancer Prostate cancer and BPH frequently coexist; therefore, patients should be screened for the presence of prostate cancer prior to treatment with tamsulosin hydrochloride capsules and at regular intervals afterwards. 5.5 Intraoperative Floppy Iris Syndrome Intraoperative Floppy Iris Syndrome (IFIS) has been observed during cataract and glaucoma surgery in some patients on or previously treated with alpha 1 blockers, including tamsulosin hydrochloride capsules [see Adverse Reactions (6.2)]. Most reports were in patients taking the alpha 1 blocker when IFIS occurred, but in some cases, the alpha 1 blocker had been stopped prior to surgery. In most of these cases, the alpha 1 blocker had been stopped recently prior to surgery (2 to 14 days), but in a few cases, IFIS was reported after the patient had been off the alpha 1 blocker for a longer period (5 weeks to 9 months). IFIS is a variant of small pupil syndrome and is characterized by the combination of a flaccid iris that billows in response to intraoperative irrigation currents, progressive intraoperative miosis despite preoperative dilation with standard mydriatic drugs and potential prolapse of the iris toward the phacoemulsification incisions. The patient's ophthalmologist should be prepared for possible modifications to their surgical technique, such as the utilization of iris hooks, iris dilator rings, or viscoelastic substances. IFIS may increase the risk of eye complications during and after the operation. The benefit of stopping alpha 1 blocker therapy prior to cataract or glaucoma surgery has not been established. The initiation of therapy with tamsulosin in patients for whom cataract or glaucoma surgery is scheduled is not recommended. 5.6 Sulfa Allergy In patients with sulfa allergy, allergic reaction to tamsulosin hydrochloride capsules has been rarely reported. If a patient reports a serious or life-threatening sulfa allergy, caution is warranted when administering tamsulosin hydrochloride capsules.

    Does Tamsulosin interact with other medications or foods?

    Tamsulosin has 10 documented drug interaction(s) and 0 food interaction(s) in clinical databases. Always provide your complete medication list to your clinician.

    This information is educational — not medical advice.

    This page is provided for general educational purposes and summarizes publicly available data from sources such as the U.S. Food & Drug Administration. It is not a substitute for the judgment of a licensed clinician and should not be used to start, stop, or change any medication. It may be incomplete or out of date, and individual circumstances vary. Always talk with your prescriber or pharmacist about your specific medications and health conditions. If you think you may have a medical emergency, call 911.

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