Flomax dosage, forms, and strengths

Flomax is a brand-name prescription drug that treats the symptoms of benign prostatic hyperplasia or BPH (enlarged prostate). Doctors sometimes use it off-label to help adults or children pass kidney stones. The active ingredient in Flomax, tamsulosin hydrochloride, is an alpha blocker that makes it easier to urinate by relaxing the muscles in the bladder neck and prostate. Doses are taken once daily, 30 minutes after a meal.

Check our best Flomax prices

RELATED: Get Flomax discounts | What is Flomax?

Flomax dosage for benign prostatic hyperplasia

The FDA has approved Flomax only as a treatment for urinary symptoms due to an enlarged prostate. Daily doses will help relieve difficulty urinating, painful urination, frequent urination, and other problems. Doses are taken once daily, 30 minutes after the same meal each day. For instance, if doses are taken after dinner, they should always be taken 30 minutes after dinner every day. 

Flomax dosage for kidney stones

Healthcare providers frequently use Flomax to help people pass symptomatic or painful kidney stones (medical expulsive treatment). This is an unapproved or “off-label” use, but most people given tamsulosin will pass stones earlier and less painfully than they otherwise would. Patients take a 0.4 mg capsule once daily at bedtime for up to 28 days or until the stone passes.

Flomax safety info

Flomax is a safe drug to take, but side effects are common. Many patients will experience problems like headache, runny nose, dizziness, lightheadedness, infection, weakness, back pain, and abnormal ejaculation problems. Serious but uncommon adverse effects include low blood pressure (hypotension), prolonged and painful erections (priapism), blurred vision, chest pain, and severe drug reactions.

Flomax is never safe to take by people who have had an allergic reaction to tamsulosin. Patients should inform the healthcare provider if they are allergic to sulfa drugs.

Dose adjustments are not required for people with liver or renal impairment, but tell the healthcare provider if you have kidney or liver problems. 

Tamsulosin can cause difficulties for certain types of eye surgeries, including glaucoma and cataract surgery. Tell the surgeon that you are taking tamsulosin before the procedure is scheduled.

Because tamsulosin can mask the symptoms of prostate cancer, patients will need to be screened for cancer before taking the drug.

While tamsulosin is not FDA-approved for use in women, healthcare professionals may use it off-label in women with kidney stones. Though research has shown it to be safe during pregnancy, women who are pregnant or breastfeeding should ask the prescriber for medical advice before starting Flomax.

Drug interactions are another potential problem. Doctors will avoid prescribing it with other alpha blockers, drugs that lower blood pressure, erectile dysfunction drugs, or drugs that strongly interfere with the body’s ability to break down tamsulosin. Tell the prescriber about all the prescription drugs, over-the-counter medications, and supplements that are regularly used before taking Flomax.

Certain foods, like grapefruit products and alcohol, might increase the risk of side effects.

How to take Flomax

Flomax should be taken by mouth, once per day. Flomax should be taken 30 minutes after a meal to ensure that the maximum concentration of the medication circulating in the bloodstream isn’t reached too quickly. Do not take a dose of tamsulosin on an empty stomach.

• Swallow the capsule whole. Do not crush, chew, or open it.

  • For children who are unable to swallow a capsule, there is data to support opening the capsule and sprinkling the contents into a soft and cool food like pudding or yogurt. The child must be careful not to chew the granules and only gently swallow them.

• If you have missed a dose, take a dose after a meal as soon as you remember. 

  • If you’ve missed an entire day’s dose, skip the missed dose and take the next dose at its regular time.

  • If you forget to take this medicine for several days in a row, talk to your healthcare provider before restarting doses. You will likely have to restart and at the lowest dose and titrate as needed.

• Store the medicine in a closed container at room temperature.

Flomax dosage FAQs

How long does it take Flomax to work?

Flomax usually begins to work rapidly, but in some individuals, improvement may take two to four weeks. In clinical studies, most Flomax users have been shown to have symptom improvement for at least five years while taking the medication. 

Should I take Flomax in the morning or at night?

For BPH, Flomax can be taken in the morning or at night. Take the dose 30 minutes after the same meal every day. If taken in the morning, always take the dose after breakfast. If taken at night, always take the dose after dinner.

How much Flomax can you take in a day?

The maximum daily dose of Flomax is 0.8 mg per day (two capsules). However, never exceed the prescribed dose.

How long can you take Flomax?

Long-term treatment with Flomax is considered safe and well-tolerated in most people with lower urinary tract symptoms and BPH. Treatment can continue indefinitely as long as the drug works and the side effects of tamsulosin are tolerable. 

What is the dosage of Flomax for dogs and cats?

Veterinarians commonly use generic Flomax (tamsulosin) in dogs and cats to treat the symptoms of BPH. They may also use it to treat urethrospasm associated with inflammation or stones in the ureter. The typical veterinary dosages of Flomax are 0.1 - 0.2 mg/10 kg/day for dogs and 0.004 - 0.006 mg/kg/day for cats.

Sources:

• Flomax drug summary, Prescriber’s Digital Reference (PDR)

• Flomax tamsulosin capsule prescribing information, DailyMed (NIH National Library of Medicine)

• Tamsulosin: current clinical experience, Urology

• Drugs used to manage urinary incontinence in dogs and cats, Plumb’s Therapeutics Brief

• Long-term efficacy and safety of tamsulosin for BPH, Reviews in Urology

• Long-term use of tamsulosin to treat lower urinary tract symptoms/BPH, Journal of Urology 

• Discontinuation of tamsulosin treatment in men with lower urinary tract symptoms: A pilot study, Urologia Internationalis

• Safety and efficacy of tamsulosin as medical expulsive therapy in pregnancy, World Journal of Urology 

• Tamsulosin and spontaneous passage of ureteral stones in children: a multi-institutional cohort study, Epub (2014)