I am a 58-year-old man diagnosed with BPH about 12 months ago. My PSA was 1.95 ng/mL, prostate volume was 43 cc and post-void residual urine was 40 cc. My physician prescribed Tamdura, which I have taken for one year.
At my recent check-up, my PSA was 0.89 ng/mL, prostate volume was 36 cc and post-void residual was 17 cc. My physician advised me to continue the same medicine for another six months.
Will this medicine eventually shrink my prostate to a normal size so that I can stop treatment? What are the possible long-term side effects?
Quick Answer
Your results show several changes that are generally consistent with a response to treatment:
- prostate volume decreased from 43 cc to 36 cc;
- post-void residual urine decreased from 40 cc to 17 cc;
- PSA decreased from 1.95 to 0.89 ng/mL.
If Tamdura contains dutasteride plus tamsulosin, the reduction in prostate size and PSA is mainly attributable to dutasteride. Tamsulosin helps relax the prostate and bladder outlet and can improve urinary flow and symptoms, but it does not significantly shrink the prostate.
A prostate does not have to return to a particular “normal” size before treatment can be stopped. The decision to continue, reduce or change treatment depends on symptoms, urinary flow, residual urine, prostate size, risk of urinary retention and how well the medication is tolerated.
One particularly important point is that dutasteride commonly lowers PSA. Therefore, future PSA results must be interpreted in the context of ongoing dutasteride treatment.
What Do These Original Results Mean?
Let us look at the three measurements separately rather than treating them as one number.
PSA 1.95 ng/mL
A PSA of 1.95 ng/mL at age 58 is not, by itself, a diagnosis of either BPH or prostate cancer.
PSA is produced by prostate tissue and may be influenced by prostate size, age, inflammation, infection, ejaculation, urinary retention, instrumentation and prostate cancer.
The important point is that PSA must always be interpreted in clinical context. You can read more in my guide to PSA and prostate problems .
Prostate volume of 43 cc
A volume of 43 cc indicates an enlarged prostate, but it is not an extremely large gland.
Prostate volume matters because men with larger prostates have a greater risk of BPH progression over time, including worsening symptoms, acute urinary retention and the possible need for surgery.
Current European guidance specifically considers prostate volume above about 40 mL one factor that may support treatment with a 5-alpha-reductase inhibitor in men who have moderate-to-severe urinary symptoms and an increased risk of progression.
Post-void residual of 40 cc
Post-void residual, or PVR, measures how much urine remains in the bladder after you have urinated.
A PVR of 40 cc is relatively modest and is very different from severe chronic retention involving several hundred milliliters.
However, PVR should not be interpreted using a single rigid cut-off. Doctors consider the value together with urinary symptoms, urine-flow measurements, bladder function and whether the residual is increasing or decreasing over time.
What Do the New Results Show?
| Measurement | Before Treatment | After About 1 Year | Interpretation |
|---|---|---|---|
| PSA | 1.95 ng/mL | 0.89 ng/mL | A substantial reduction. Dutasteride itself commonly lowers PSA, so this is an expected medication effect and must be considered when interpreting future PSA tests. |
| Prostate volume | 43 cc | 36 cc | Approximately 16% smaller. This is compatible with the prostate-shrinking effect of dutasteride. |
| Post-void residual | 40 cc | 17 cc | Less urine remains after urination, which generally suggests improved bladder emptying. |
Which Part of Tamdura Shrinks the Prostate?
If the Tamdura formulation you are taking contains dutasteride and tamsulosin, the two medicines have different jobs.
Dutasteride
Dutasteride is a 5-alpha-reductase inhibitor.
It blocks conversion of testosterone to dihydrotestosterone, or DHT, which is an important androgen involved in prostate growth.
Over time, this can reduce prostate volume.
Clinical guideline data indicate that 5-alpha-reductase inhibitors can reduce prostate volume by roughly 18–28% during long-term treatment. They also lower the long-term risk of acute urinary retention and BPH-related surgery in appropriately selected men.
Tamsulosin
Tamsulosin is an alpha-1 blocker.
It relaxes smooth muscle in and around the prostate and bladder outlet, allowing urine to pass more easily.
It often works considerably faster than dutasteride and can improve symptoms such as:
- weak urine stream;
- hesitancy;
- straining;
- incomplete emptying;
- and other lower urinary tract symptoms.
The reduction from 43 cc to 36 cc should therefore not be attributed mainly to tamsulosin. The prostate-volume reduction is much more consistent with the effect of dutasteride.
Is a Reduction From 43 cc to 36 cc Good?
Yes, it is a meaningful reduction.
A change from 43 cc to 36 cc is approximately a 16% decrease in measured volume.
Guideline data suggest that 5-alpha-reductase inhibitors typically reduce prostate volume by approximately 18–28% after longer-term treatment, although individual responses vary.
Measurements also have some natural variation depending on imaging technique and who performs the measurement, so the exact number should not be treated as perfectly precise.
What is reassuring in your case is that the prostate measurement decreased at the same time that the post-void residual also decreased. Those changes together are more informative than prostate size alone.
Does the Prostate Need to Return to a “Normal” Size?
No.
The goal of BPH treatment is not necessarily to return the prostate to the size it had when you were younger.
The more important goals are to:
- reduce bothersome urinary symptoms;
- maintain good bladder emptying;
- improve urinary flow where possible;
- reduce the risk of acute urinary retention;
- reduce the risk of BPH progression;
- and avoid complications or surgery when possible and appropriate.
A man can have a somewhat enlarged prostate and function very well. Conversely, another man can have a smaller prostate but significant urinary obstruction.
That is why treatment decisions should not be made from prostate volume alone.
Will Dutasteride Continue Shrinking the Prostate?
It may produce further reduction, but there is no way to predict that your prostate will continue shrinking until it reaches a particular number.
Dutasteride has a slow onset of action. Its clinical effect develops over months, and the medication is generally intended as a long-term BPH treatment rather than a short course that is automatically stopped once the prostate becomes smaller.
This is quite different from an antibiotic, for example, where a patient takes the medicine for a defined short period and then stops.
With BPH, your doctor weighs the ongoing benefits against side effects and your risk of future progression.
Why Might My Doctor Recommend Another Six Months?
Your physician may have several reasonable reasons for continuing treatment.
You began with an enlarged prostate of approximately 43 cc, and after treatment you have:
- a smaller measured prostate;
- a lower residual urine volume;
- and a PSA reduction consistent with dutasteride exposure.
If your urinary symptoms have also improved and you are tolerating treatment, continuing therapy may be appropriate.
Current EAU guidance specifically states that 5-alpha-reductase inhibitors are suitable for long-term treatment measured in years because their onset of action is slow and their benefits include reducing the risk of BPH progression.
Dr. Albana’s Perspective
Looking at these numbers together, I would consider the direction of change encouraging.
Your prostate volume decreased from 43 cc to 36 cc, while the amount of urine remaining after urination fell from 40 cc to 17 cc. Those changes suggest that your treatment may be helping.
But I would not tell you that you can stop treatment simply because the prostate becomes smaller. Nor would I tell you that the medicine must continue forever.
I would want to know how you actually feel: whether your urine stream is stronger, whether you still strain, how often you wake at night, whether you have urgency, and whether you feel that your bladder empties properly.
I would also pay particular attention to your PSA. Dutasteride can reduce PSA substantially, so a PSA of 0.89 ng/mL after treatment cannot be interpreted in exactly the same way as a PSA of 0.89 ng/mL in a man who is not taking a 5-alpha-reductase inhibitor.
For that reason, continue following your physician’s PSA monitoring plan and make sure every clinician interpreting your PSA knows that you are taking dutasteride.
— Dr. Albana Greca, MD, MMedSc
Family Physician / General Practitioner
Why Did My PSA Fall From 1.95 to 0.89?
This is an especially important part of your question.
Dutasteride commonly lowers serum PSA by approximately 50% within the first several months of treatment.
Your PSA fell from 1.95 to 0.89 ng/mL, which is a reduction of roughly 54%. That is therefore very compatible with the expected pharmacological effect of dutasteride.
Dutasteride changes the baseline against which later PSA measurements are interpreted. Once a new PSA baseline or nadir has been established, a confirmed rise from that low point deserves medical assessment even if the absolute PSA number still appears relatively low.
You can read more about PSA interpretation in my PSA guide .
What Are the Long-Term Side Effects?
Because combination therapy contains two medicines, possible adverse effects come from both dutasteride and tamsulosin.
Possible Dutasteride Side Effects
The most clinically relevant adverse effects involve sexual function. Possible effects include:
- reduced sexual desire;
- erectile dysfunction;
- ejaculatory problems;
- reduced semen volume;
- breast tenderness;
- and breast enlargement.
Mood symptoms have also been reported with 5-alpha-reductase inhibitors. Persistent depressed mood or other significant psychological symptoms should be discussed with a clinician.
Possible Tamsulosin Side Effects
Tamsulosin can cause:
- dizziness;
- lightheadedness, particularly when standing;
- low blood pressure in some patients;
- ejaculatory dysfunction;
- nasal symptoms;
- and occasionally other adverse effects.
One important issue that patients sometimes overlook is intraoperative floppy iris syndrome.
If you are planning cataract or glaucoma surgery, tell the ophthalmologist that you currently take—or previously took—tamsulosin.
Do Side Effects Usually Begin Only After One or Two Years?
No. There is no reliable rule that these side effects normally start only after one or two years.
Some adverse effects can occur relatively early, some develop later, and many patients never experience significant problems at all.
Being free of troublesome side effects after one year is reassuring in the sense that you are currently tolerating the medication, but it does not guarantee that no side effect can appear later.
Likewise, developing a side effect does not mean another drug can simply “cure” it. Management depends on which symptom occurs, its severity, other medications and whether the benefits of continuing therapy still outweigh the disadvantages.
Can Combination Treatment Be Used Long Term?
Yes, in appropriately selected men.
Combination therapy with an alpha-blocker and 5-alpha-reductase inhibitor is specifically used when long-term treatment is intended, particularly in men with moderate-to-severe urinary symptoms and an enlarged prostate who have a higher risk of BPH progression.
Large clinical trials have shown that long-term combination treatment can provide greater symptom improvement and reduce the risk of acute urinary retention or BPH-related surgery compared with alpha-blocker treatment alone in appropriate patients.
However, combination therapy also produces more adverse effects than either medicine alone. That is why the treatment should periodically be reviewed rather than continued automatically without reassessment.
Can Tamsulosin Ever Be Stopped While Dutasteride Continues?
Sometimes, but this decision is individualized.
Because tamsulosin provides relatively rapid symptom relief whereas dutasteride works gradually, some men who have done well after a sustained period of combination treatment may be considered for withdrawal of the alpha-blocker while continuing the 5-alpha-reductase inhibitor.
That approach is not right for every patient. Men who still have troublesome symptoms may deteriorate when the alpha-blocker is removed.
Therefore, do not stop only one component yourself. If the goal is eventually to reduce medication, ask your physician whether your symptoms, flow and residual urine make a supervised treatment adjustment reasonable.
When Should You Contact Your Doctor?
Contact your doctor if you develop:
- persistent dizziness or fainting;
- new or troublesome erectile or ejaculatory problems;
- significant loss of libido;
- breast lumps, persistent breast pain or nipple discharge;
- new or worsening depression;
- a significant change in urinary symptoms;
- recurrent urinary infections;
- visible blood in the urine;
- or a confirmed rise in PSA from the new baseline established while taking dutasteride.
When Urinary Symptoms Need Urgent Attention
Seek urgent medical care if you become completely unable to urinate, particularly if your lower abdomen becomes painful or swollen.
You should also seek prompt assessment for fever and chills with painful urination, severe urinary bleeding or other signs of serious infection or obstruction.
Acute urinary retention generally requires prompt bladder drainage and medical evaluation.
Questions to Ask at Your Next BPH Review
- How have my urinary symptoms changed compared with one year ago?
- Is my post-void residual of 17 cc satisfactory for me?
- Do I need another urinary-flow test?
- How should my PSA be interpreted while I am taking dutasteride?
- What PSA level is being used as my new baseline or nadir?
- Should I continue both dutasteride and tamsulosin?
- Could the tamsulosin component eventually be withdrawn if my symptoms remain controlled?
- What side effects should prompt me to contact you?
- How often should my prostate, PSA and urinary symptoms be reassessed?
Frequently Asked Questions
Is a prostate size of 43 cc very large?
A 43 cc prostate is enlarged, but it is not extremely large. Size should be interpreted together with urinary symptoms, urine flow, post-void residual and other clinical findings.
Is a PVR of 40 cc dangerous?
A post-void residual of 40 cc is relatively modest and is not comparable with severe chronic urinary retention involving much larger volumes. Its importance depends on symptoms, bladder function and whether the residual is increasing. In this case, the later measurement of 17 cc represents an improvement.
Can dutasteride shrink the prostate?
Yes. Dutasteride is a 5-alpha-reductase inhibitor and can gradually reduce prostate volume. Guideline data suggest reductions of approximately 18–28% during longer-term therapy, although individual results vary.
Does tamsulosin shrink the prostate?
No. Tamsulosin primarily relaxes smooth muscle around the prostate and bladder outlet to improve urinary symptoms and flow. It does not significantly reduce prostate volume.
Why did PSA fall after starting dutasteride?
Dutasteride commonly lowers PSA by approximately 50% within several months. This is an expected medication effect. Doctors must take the medication into account when interpreting subsequent PSA measurements.
Can I stop the medicine when my prostate becomes smaller?
Not automatically. The decision depends on urinary symptoms, prostate size, bladder emptying, risk of progression, side effects and your physician’s assessment. Dutasteride is generally intended for long-term treatment when it is used to reduce BPH progression risk.
Related Guides
Medical References
-
European Association of Urology.
EAU Guidelines on the Management of Non-neurogenic Male Lower Urinary
Tract Symptoms — Disease Management.
EAU Male LUTS Guideline -
U.S. National Library of Medicine.
Dutasteride and Tamsulosin Hydrochloride Prescribing Information.
DailyMed.
DailyMed -
National Institute of Diabetes and Digestive and Kidney Diseases.
Enlarged Prostate (Benign Prostatic Hyperplasia).
NIDDK
Medical information notice: This page provides general patient education and cannot determine whether an individual patient should continue, stop or modify BPH medication. Treatment depends on urinary symptoms, prostate size, bladder emptying, PSA interpretation, risk of disease progression, side effects and the treating clinician’s assessment. Do not stop dutasteride or tamsulosin without discussing the decision with your doctor.
Written & medically reviewed by Dr. Albana Greca, MD, MMedSc • Family Physician / General Practitioner • Last medically reviewed: August 2026