Finasteride and Tamsulosin Together: What the Labels Say

This page sticks to label facts: what each drug does, what the labels say about using them together, and what to watch for. We do not give doses. The doctor treating your prostate decides the plan.

How finasteride and tamsulosin each work

An enlarged prostate, called benign prostatic hyperplasia or BPH, squeezes the tube that carries urine. Peeing gets slow, weak or frequent. The two drugs attack that problem from two sides.

MedlinePlus describes tamsulosin simply: "It works by relaxing the muscles in the prostate and bladder so that urine can flow easily" (MedlinePlus: tamsulosin, read 14 Nov 2026). For finasteride, it says the drug "treats BPH by blocking the body's production of a male hormone that causes the prostate to enlarge" (MedlinePlus: finasteride). That hormone is DHT.

What the labels say about taking both

Neither label names the other drug in its approved uses. The Proscar label approves finasteride with a different alpha blocker, doxazosin: "PROSCAR administered in combination with the alpha-blocker doxazosin is indicated to reduce the risk of symptomatic progression of BPH" (DailyMed: Proscar label). Tamsulosin belongs to the same drug family as doxazosin. The finasteride and tamsulosin pair itself is not a labelled combination.

On interactions, the Flomax label reports lab work with liver enzymes. It found no sign that tamsulosin and finasteride change how the liver breaks each other down. The Proscar label adds that finasteride was used in its studies alongside "α-blockers" and other common drugs "without evidence of clinically significant adverse interactions" (DailyMed: Proscar label). Alpha blockers is the family name that covers tamsulosin.

What the combination study found

The best data on finasteride plus an alpha blocker comes from the MTOPS study in the Proscar label. It followed 3,047 men with BPH for about five years. They were split into four groups: finasteride, doxazosin, both together, or a dummy pill (a placebo) for comparison.

Against the dummy pill, the risk of symptoms getting clearly worse "was reduced by 30%" with finasteride alone, 46% with doxazosin alone, and 64% with both (DailyMed: Proscar label). The label says the pair "significantly reduced the risk of symptom score progression compared to the effect of PROSCAR alone". That study used doxazosin, not tamsulosin, so treat it as a guide to the approach, not to your exact pills.

Side effects that can add up

The same study listed the side effects that were more common with both drugs than with either one. The label names "asthenia, postural hypotension, peripheral edema, dizziness, decreased libido, rhinitis, abnormal ejaculation, impotence and abnormal sexual function" (DailyMed: Proscar label). In plain words: weakness, a drop in blood pressure when you stand up, swollen ankles, dizziness, lower sex drive, a stuffy nose, ejaculation changes and erection trouble.

Ejaculation is the clearest overlap. Each drug affects it on its own:

The Flomax label explains that abnormal ejaculation "includes ejaculation failure, ejaculation disorder, retrograde ejaculation, and ejaculation decrease". Retrograde ejaculation means semen goes back into the bladder instead of out.

Tamsulosin warnings to know

The Flomax label carries a few warnings that do not apply to finasteride, so they are new when you add tamsulosin.

• Dizziness on standing. The label says signs of a blood pressure drop on standing "were detected more frequently in FLOMAX capsule-treated patients than in placebo recipients". Stand up slowly, especially at first.
• Eye surgery. A problem called floppy iris syndrome "has been observed during cataract and glaucoma surgery in some patients on or previously treated with alpha 1 blockers, including FLOMAX capsules". Tell your eye surgeon you take or took it.
• Long erections. Very rarely, tamsulosin "has been associated with priapism (persistent painful penile erection unrelated to sexual activity)". That needs urgent care.
• Sulfa allergy. Men with a serious sulfa allergy should tell the prescriber.

The PSA test: tell your doctor about finasteride

This one matters when you take both. Finasteride lowers PSA, the blood test used to screen for prostate cancer. The Proscar label says it "reduces serum prostate specific antigen (PSA) levels by approximately 50%" (DailyMed: Proscar label). The Flomax label, for its part, says "patients should be screened for the presence of prostate cancer prior to treatment with FLOMAX capsules and at regular intervals afterwards". Whoever reads your PSA result needs to know you take finasteride.

Alcohol with the pair

Finasteride has no alcohol warning on its label. Tamsulosin is different. The federal alcohol institute lists Flomax under enlarged prostate drugs, with "Dizziness, light headedness, fainting" as the risk when mixed with alcohol (NIAAA: Harmful Interactions, read 14 Nov 2026). Our finasteride and alcohol guide covers drinking on finasteride.

Combination capsules

MedlinePlus lists Jalyn as a combination product "containing Dutasteride, Tamsulosin" and notes "This branded product is no longer on the market" (MedlinePlus: tamsulosin). That capsule uses dutasteride, not finasteride. Entadfi is an approved capsule that pairs finasteride with tadalafil for BPH. Our tadalafil for BPH guide covers that drug. Our finasteride vs dutasteride guide compares the two hormone blockers.

Where online programs fit

The online programs we track sell finasteride for hair loss, not tamsulosin or finasteride for the prostate. Prostate care usually runs through your own doctor or a urologist. For hair loss, generic finasteride starts at $0.83 a tablet at Strut Health, as checked November 14, 2026. Every hair loss plan is on our finasteride price page, and the ranked programs are on Best men's health programs. If you already take finasteride for the prostate, do not add a hair loss plan on top without telling both prescribers.