What the label lists and what reports show
Dutasteride and tamsulosin side effects
Dutasteride and tamsulosin's FDA label: “The most common adverse reactions, reported in ≥1% of subjects treated with coadministered dutasteride and tamsulosin are ejaculation disorders, impotence, decreased libido, dizziness, and breast disorders.” FAERS holds 1,044 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is dizziness (72 reports).
- Generic listed
Check it at the source: the dutasteride and tamsulosin FDA label on DailyMed (effective March 9, 2026, Waylis Therapeutics); the FDA FAERS public dashboard.
What does the patient leaflet say about side effects?
From the patient leaflet: What are the possible side effects of JALYN?JALYN may cause serious side effects including: Decreased blood pressure. JALYN may cause a sudden drop in your blood pressure upon standing from a sitting or lying position, especially at the start of treatment. Symptoms of low blood pressure may include: fainting dizziness feeling lightheaded Rare and serious allergic reactions, including: swelling of your face, tongue, or throat difficulty breathing serious skin reactions, such as skin peeling Get medical help right away if you have these serious allergic reactions. Higher chance of a more serious form of prostate cancer. Eye problems during cataract or glaucoma surgery. During cataract or glaucoma surgery, a condition called Intraoperative Floppy Iris Syndrome (IFIS) can happen if you take or have taken JALYN in the past. If you need to have cataract or glaucoma surgery, tell your surgeon if you take or have taken JALYN. […]
Source: FDA drug label, Waylis Therapeutics, effective March 9, 2026 (SPL set aab9a2d4-5328-40f3-986f-e7753a928bc0), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsThe most common adverse reactions, reported in ≥1% of subjects treated with coadministered dutasteride and tamsulosin are ejaculation disorders, impotence, decreased libido, dizziness, and breast disorders.
Table 1. Adverse Reactions Reported over a 48-Month Period in ≥1% of Subjects and More Frequently in the Coadministration Therapy Group than the Dutasteride or Tamsulosin Monotherapy Group (CombAT) by Time of Onset
| Reaction | (n = 1,610) (n = 1,623) (n = 1,611) | (n = 1,527) (n = 1,548) (n = 1,545) | (n = 1,428) (n = 1,464) (n = 1,468) | (n = 1,283) (n = 1,325) (n = 1,281) | (n = 1,200) (n = 1,200) (n = 1,112) |
|---|---|---|---|---|---|
| Coadministration | 7.8% | 1.6% | 1.0% | 0.5% | <0.1% |
| Dutasteride | 1.0% | 0.5% | 0.5% | 0.2% | 0.3% |
| Tamsulosin | 2.2% | 0.5% | 0.5% | 0.2% | 0.3% |
| Coadministration | 5.4% | 1.1% | 1.8% | 0.9% | 0.4% |
| Dutasteride | 4.0% | 1.1% | 1.6% | 0.6% | 0.3% |
| Tamsulosin | 2.6% | 0.8% | 1.0% | 0.6% | 1.1% |
| Coadministration | 4.5% | 0.9% | 0.8% | 0.2% | 0.0% |
| Dutasteride | 3.1% | 0.7% | 1.0% | 0.2% | 0.0% |
| Tamsulosin | 2.0% | 0.6% | 0.7% | 0.2% | <0.1% |
| Coadministration | 1.1% | 1.1% | 0.8% | 0.9% | 0.6% |
| Dutasteride | 0.9% | 0.9% | 1.2% | 0.5% | 0.7% |
| Tamsulosin | 0.4% | 0.4% | 0.4% | 0.2% | 0.0% |
| Coadministration | 1.1% | 0.4% | 0.1% | <0.1% | 0.2% |
| Dutasteride | 0.5% | 0.3% | 0.1% | <0.1% | <0.1% |
| Tamsulosin | 0.9% | 0.5% | 0.4% | <0.1% | 0.0% |
Rows and numbers as the label prints them, under its own column headings (the first rows of a longer table where it runs on). A reaction in a trial table is not necessarily caused by the medicine, and trials differ from everyday use.
From the label: adverse reactions, continuedThe most common adverse reactions, reported in ≥1% of subjects treated with coadministered dutasteride and tamsulosin are ejaculation disorders, impotence, decreased libido, dizziness, and breast disorders. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Waylis Therapeutics LLC at 1-844-200-7910 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience The clinical efficacy and safety of coadministered dutasteride and tamsulosin, which are individual components of JALYN, have been evaluated in a multicenter, randomized, double-blind, parallel group trial (the Combination with Alpha-Blocker Therapy, or CombAT, trial). Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared with rates in the clinical trial of another drug and may not reflect the rates observed in practice. The most common adverse reactions reported in subjects receiving coadministered dutasteride and tamsulosin were impotence, decreased libido, breast disorders (including breast enlargement and tenderness), ejaculation disorders, and dizziness. Ejaculation disorders occurred significantly more in subjects receiving coadministration therapy (11%) compared with those receiving dutasteride (2%) or tamsulosin (4%) as monotherapy. …
Source: FDA drug label, Waylis Therapeutics, effective March 9, 2026 (SPL set aab9a2d4-5328-40f3-986f-e7753a928bc0), via openFDA; the full label on DailyMed
What do FAERS reports show?
1,044 reports list dutasteride and tamsulosin among the medicines taken, each a report of something that happened, not proof the medicine caused it; 58 are coded as a death and 190 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Of the 23 reactions below, 13 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.
Reports received each year
The 25 most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms
What next?
- Dutasteride and tamsulosin: the full record
- label, generics, price, shortages, recalls
- Report a side effect to the FDA
- MedWatch
- Side effects hub
- the most reported medicines and reactions