Avodart (Dutasteride)
5-alpha reductase inhibitor for the treatment of benign prostatic hyperplasia (BPH)
📊 Quick Facts About Avodart
💡 Key Takeaways About Avodart
- Shrinks the prostate: Avodart reduces DHT levels by more than 90%, causing the prostate to shrink and alleviating urinary symptoms of BPH
- Long-term treatment: Full effects may take 3 to 6 months or more; do not stop treatment without consulting your doctor
- Sexual side effects possible: Erectile dysfunction, decreased libido, and ejaculation problems can occur and may persist after stopping the drug
- Not for women or children: Avodart must never be taken by women, children, or adolescents; pregnant women must not handle leaking capsules
- Affects PSA tests: Avodart approximately halves PSA levels, which can affect prostate cancer screening; inform your doctor that you are taking this medication
What Is Avodart and What Is It Used For?
Avodart (dutasteride) is a prescription medication used to treat men with benign prostatic hyperplasia (BPH), a non-cancerous enlargement of the prostate gland. By inhibiting both type 1 and type 2 5-alpha reductase enzymes, it reduces dihydrotestosterone (DHT) levels by more than 90%, leading to prostate shrinkage and relief from urinary symptoms.
Benign prostatic hyperplasia is one of the most common conditions affecting older men. As the prostate gland grows, it can compress the urethra and cause a range of lower urinary tract symptoms (LUTS) that significantly impact quality of life. These symptoms include difficulty initiating urination, a weak or intermittent urine stream, the sensation of incomplete bladder emptying, and the need to urinate frequently, especially during the night (nocturia).
Avodart belongs to a class of drugs known as 5-alpha reductase inhibitors. The prostate gland depends on dihydrotestosterone (DHT) for its growth. DHT is produced from testosterone by the enzyme 5-alpha reductase, which exists in two forms (type 1 and type 2). Unlike finasteride, which inhibits only the type 2 isoenzyme, dutasteride inhibits both type 1 and type 2, resulting in a more complete suppression of DHT production. Clinical studies have demonstrated that dutasteride reduces serum DHT levels by more than 90% within two weeks of initiating therapy.
By reducing DHT levels, Avodart causes the enlarged prostate to gradually shrink in size. Over time, this leads to measurable improvements in urinary flow rate, reduction of symptoms, and a decreased risk of acute urinary retention (a sudden inability to urinate that requires emergency catheterization) and the need for surgical intervention. In pivotal clinical trials, dutasteride reduced the risk of acute urinary retention by 57% and the risk of BPH-related surgery by 48% over a four-year treatment period.
Combination Therapy with Tamsulosin
Avodart may also be prescribed in combination with tamsulosin, an alpha-adrenergic blocker that relaxes smooth muscle in the prostate and bladder neck. This combination therapy, studied in the landmark CombAT (Combination of Avodart and Tamsulosin) trial, has been shown to provide greater symptom relief and risk reduction than either drug alone. The combination is particularly beneficial for men with larger prostates (over 30–40 mL) who are at higher risk of disease progression.
The European Association of Urology (EAU) and the American Urological Association (AUA) both recommend combination therapy with a 5-alpha reductase inhibitor and an alpha-blocker for men with moderate-to-severe LUTS and demonstrable prostate enlargement, as this approach addresses both the static (prostate size) and dynamic (smooth muscle tone) components of urinary obstruction.
Avodart is a long-term treatment. Some men notice an early improvement in symptoms, but it may take 6 months or more of continuous use before the full benefit is realized. Maximum prostate volume reduction is typically achieved after 1 to 2 years of treatment. Do not stop taking Avodart without consulting your doctor.
What Should You Know Before Taking Avodart?
Before taking Avodart, inform your doctor about any liver problems, allergies to soy or peanuts, and all other medications you are taking. Avodart is contraindicated in women, children, and men with severe liver disease. Pregnant women must not handle leaking capsules. Men taking Avodart should use condoms during sexual intercourse to prevent exposure of a pregnant partner to dutasteride through semen.
While Avodart is generally well tolerated, certain conditions and circumstances require careful consideration before starting treatment. Your prescribing physician will evaluate your individual risk factors and medical history to determine whether dutasteride is appropriate for you.
Contraindications
You should not take Avodart if:
- You are allergic to dutasteride, any other 5-alpha reductase inhibitor, soy, peanuts, or any of the other ingredients in the capsules
- You have severe liver impairment (severe hepatic insufficiency), as dutasteride is extensively metabolized by the liver
- You are a woman, child, or adolescent – this medication is only for use by adult men
Warnings and Precautions
Talk to your doctor before taking Avodart if you have or have had any condition affecting your liver. Patients with mild to moderate hepatic impairment may require additional monitoring during treatment, as reduced liver function can alter the metabolism and clearance of dutasteride from the body.
Women and skin contact: Women, children, and adolescents must not handle leaking Avodart capsules because the active ingredient can be absorbed through the skin. If accidental skin contact with the capsule contents occurs, the affected area should be washed immediately and thoroughly with soap and water. Intact capsules can be handled safely.
Condom use during intercourse: Dutasteride has been detected in the semen of men taking Avodart. If your partner is or may become pregnant, you must use a condom to prevent her from coming into contact with your semen, as dutasteride could affect the normal development of a male fetus. Dutasteride has also been shown to reduce sperm count, semen volume, and sperm motility, which may reduce male fertility.
PSA (Prostate-Specific Antigen) testing: Avodart affects PSA blood levels, which are sometimes used to screen for prostate cancer. Dutasteride approximately halves serum PSA concentrations after about 6 months of treatment. If you are scheduled for a PSA blood test, always inform your doctor or the laboratory that you are taking Avodart, so that your results can be correctly interpreted. Men taking Avodart should have their PSA levels tested regularly.
Prostate cancer risk: In a large clinical study (the REDUCE trial) involving men at increased risk for prostate cancer, men who took dutasteride had a higher incidence of a more aggressive form of prostate cancer (Gleason score 8–10) compared to men who took placebo. The significance of this finding and the effect of dutasteride on this form of prostate cancer are not fully established. Discuss your individual risk with your doctor.
Breast changes: Avodart may cause breast enlargement (gynecomastia) and breast tenderness. If you experience breast lumps, pain, or nipple discharge, report these changes to your doctor promptly, as they may be signs of a serious condition such as breast cancer, which can rarely occur in men.
Mood changes and depression: Depressed mood, depression, and more rarely, suicidal ideation have been reported in patients taking 5-alpha reductase inhibitors, including dutasteride. If you experience any of these symptoms, contact your doctor for medical advice as soon as possible.
Pregnancy, Breastfeeding, and Fertility
Avodart is classified as a pregnancy category X medication by the FDA, meaning it is contraindicated in pregnancy. Dutasteride is absorbed through the skin and can affect the normal development of a male fetus, particularly during the first 16 weeks of gestation. Women who are pregnant or who may become pregnant must not handle leaking capsules.
Men taking dutasteride should use condoms during sexual intercourse with a female partner who is or may become pregnant. Dutasteride has been found in semen at low concentrations, and the potential risk of fetal exposure through semen has not been fully evaluated.
Dutasteride has been shown to decrease sperm count, semen volume, and sperm motility in some men. While these effects have been reversible after discontinuation in most cases, the extent to which dutasteride may impair male fertility on a long-term basis is not fully known. If you are planning to father a child, discuss the potential impact of dutasteride on fertility with your doctor.
Pregnant women must not handle leaking or broken Avodart capsules. Dutasteride is absorbed through the skin and may cause birth defects in male fetuses, especially during the first 16 weeks of pregnancy. If a pregnant woman comes into contact with dutasteride, consult a doctor immediately.
How Does Avodart Interact with Other Drugs?
Avodart is metabolized by the CYP3A4 enzyme system. Drugs that inhibit CYP3A4 – such as verapamil, diltiazem, ritonavir, ketoconazole, and itraconazole – can increase dutasteride blood levels and the risk of side effects. Always inform your doctor about all medications you are taking, including prescription, over-the-counter, and herbal products.
Drug interactions occur when the presence of one medication affects the way another medication is absorbed, distributed, metabolized, or eliminated by the body. Understanding potential interactions with Avodart is important for ensuring both the safety and efficacy of your treatment.
Dutasteride is primarily metabolized by the liver enzyme CYP3A4. Medications that inhibit this enzyme can slow the breakdown of dutasteride, leading to higher blood concentrations and potentially increasing the risk of side effects. Your doctor may need to adjust your dutasteride dose or recommend an alternative treatment if you are taking any of the following medications.
| Interacting Drug | Drug Class | Interaction Type | Clinical Significance |
|---|---|---|---|
| Verapamil | Calcium channel blocker | CYP3A4 inhibition | Increased dutasteride levels; dose adjustment may be needed |
| Diltiazem | Calcium channel blocker | CYP3A4 inhibition | Increased dutasteride levels; dose adjustment may be needed |
| Ritonavir | HIV protease inhibitor | Strong CYP3A4 inhibition | Significantly increased dutasteride levels; use with caution |
| Indinavir | HIV protease inhibitor | CYP3A4 inhibition | Increased dutasteride levels; use with caution |
| Itraconazole | Antifungal agent | Strong CYP3A4 inhibition | Significantly increased dutasteride levels; avoid combination or reduce dose |
| Ketoconazole | Antifungal agent | Strong CYP3A4 inhibition | Significantly increased dutasteride levels; avoid combination or reduce dose |
| Nefazodone | Antidepressant | CYP3A4 inhibition | Increased dutasteride levels; monitor for side effects |
| Tamsulosin | Alpha-blocker | Pharmacodynamic (additive) | Approved combination; may increase risk of dizziness |
CYP3A4 Inhibitors – Major Interactions
The most clinically significant interactions involve potent CYP3A4 inhibitors. These medications can substantially reduce the hepatic clearance of dutasteride, leading to a pronounced increase in plasma dutasteride concentrations. Strong CYP3A4 inhibitors include antifungal agents (ketoconazole, itraconazole), HIV protease inhibitors (ritonavir, indinavir), and certain other medications. If you are prescribed any of these drugs, your doctor should reassess whether dutasteride treatment should be continued or the dose adjusted.
Moderate Interactions
Moderate CYP3A4 inhibitors such as verapamil, diltiazem, and nefazodone may also increase dutasteride exposure, though to a lesser degree than strong inhibitors. While these combinations are not necessarily contraindicated, your doctor should be informed so that appropriate monitoring can be arranged. In clinical pharmacokinetic studies, verapamil co-administration decreased the clearance of dutasteride by 37% and increased the area under the curve (AUC) by 44%.
Food and Drink
Avodart can be taken with or without food. There are no specific food or drink interactions that would require dietary restrictions while taking this medication. However, grapefruit juice is a known CYP3A4 inhibitor and may theoretically increase dutasteride levels; it is prudent to consume grapefruit products in moderation or discuss this with your doctor.
What Is the Correct Dosage of Avodart?
The recommended dose of Avodart is one capsule (0.5 mg) taken once daily by mouth. Swallow the capsule whole with water – do not chew or open it. Avodart can be taken with or without food. It is a long-term treatment, and results may take 3 to 6 months or more to become apparent.
Proper dosing of Avodart is straightforward, as there is a single standard dose for all adult male patients. However, understanding the key aspects of administration, duration of treatment, and what to do in case of missed or excess doses is important for getting the best results from your therapy.
Adults
Standard Adult Dose
Dose: 0.5 mg (one soft capsule) once daily
Administration: Take by mouth with a glass of water. Swallow the capsule whole. Do not chew, crush, or open the capsule, as contact with the contents may cause irritation of the mouth and throat.
Food: Can be taken with or without food at any time of day.
Duration: Long-term treatment. Continue for as long as your doctor prescribes, even if symptoms improve.
When prescribed in combination with tamsulosin, the usual dosing is dutasteride 0.5 mg plus tamsulosin 0.4 mg daily. A fixed-dose combination capsule (marketed as Combodart or Jalyn in some countries) is available in many markets.
Children and Adolescents
Avodart is not indicated for use in children or adolescents. This medication is intended only for adult males with benign prostatic hyperplasia.
Elderly Patients
No dose adjustment is required for elderly patients. The standard dose of 0.5 mg once daily applies regardless of age. Clinical trials included men aged 50 years and older, and efficacy and safety were consistent across age groups.
Patients with Hepatic Impairment
Dutasteride is extensively metabolized in the liver. While no specific dose adjustment has been established for patients with mild to moderate hepatic impairment, these patients should be monitored carefully. Avodart is contraindicated in patients with severe hepatic impairment, as the drug has not been studied in this population and its accumulation could pose significant safety risks.
Patients with Renal Impairment
No dose adjustment is necessary for patients with kidney impairment. Only a very small fraction of dutasteride is excreted unchanged in the urine (less than 0.1%), so renal function has minimal impact on drug levels.
Missed Dose
If you forget to take your daily dose of Avodart, simply take the next dose at your usual time. Do not take a double dose to make up for the missed one. If you miss doses frequently, it may affect the monitoring of your PSA levels and the overall effectiveness of treatment.
Overdose
In single-dose clinical studies, dutasteride has been administered at doses up to 40 mg (80 times the therapeutic dose) for 7 days without significant safety concerns beyond those seen at standard doses. There is no specific antidote for dutasteride overdose. If you suspect you have taken too many capsules, contact your doctor, pharmacist, or local poison control center for advice. Treatment is supportive and symptomatic.
Do not discontinue Avodart without first consulting your doctor. Stopping treatment may allow the prostate to resume growing, leading to a return of urinary symptoms. The full therapeutic effect of dutasteride develops over several months, and the benefits are maintained only with continued use.
What Are the Side Effects of Avodart?
The most common side effects of Avodart include erectile dysfunction, decreased libido, ejaculation disorders, and breast enlargement or tenderness. These sexual side effects may persist even after stopping treatment. Uncommon side effects include heart failure and changes in body hair. Depression and testicular pain have been reported at unknown frequency.
Like all medications, Avodart can cause side effects, although not everyone who takes it will experience them. The side effects of dutasteride are generally related to its mechanism of action as an anti-androgen agent, which affects DHT-dependent tissues and functions throughout the body. Understanding the frequency and nature of these side effects can help you make informed decisions about your treatment and know when to seek medical advice.
Signs of an allergic reaction to Avodart may include skin rash (which may itch), hives (urticaria), or swelling of the eyelids, face, lips, arms, or legs. If you experience any of these symptoms, stop taking Avodart and contact your doctor immediately.
Common Side Effects
May affect up to 1 in 10 men
- Erectile dysfunction (impotence) – difficulty achieving or maintaining an erection; this may persist after discontinuing treatment
- Decreased sex drive (libido) – reduced sexual desire; this may persist after discontinuing treatment
- Ejaculation disorders – including decreased semen volume during ejaculation; this may persist after discontinuing treatment
- Gynecomastia – breast enlargement and/or tenderness
- Dizziness – particularly when taken in combination with tamsulosin
Uncommon Side Effects
May affect up to 1 in 100 men
- Heart failure – the heart becomes less efficient at pumping blood; symptoms may include shortness of breath, extreme tiredness, and swelling of the ankles and legs
- Hair changes – hair loss (usually from the body) or hair growth
Frequency Unknown
Cannot be estimated from available data
- Depression – feelings of sadness, low mood, or depressive episodes
- Testicular pain and swelling
Persistent Sexual Side Effects
An important consideration with Avodart and other 5-alpha reductase inhibitors is the potential for sexual side effects to persist after discontinuation of the medication. While most men who experience these effects find that they resolve within weeks to months after stopping treatment, some studies and patient reports suggest that erectile dysfunction, decreased libido, and ejaculation problems may continue for a prolonged period in a subset of individuals. This has been termed "post-finasteride syndrome" in the medical literature, although it remains a subject of ongoing research and debate.
If you experience persistent or worsening sexual side effects while taking Avodart, discuss these concerns with your doctor. In some cases, the benefits of continued treatment for BPH symptoms may outweigh the risks, while in others, alternative treatments may be more appropriate.
Reporting Side Effects
It is important to report suspected side effects after a medicine has been approved for use. This makes it possible to continuously monitor the benefit-risk balance of the medication. Healthcare professionals and patients can report suspected adverse reactions to their national regulatory authority (e.g., the EMA in Europe or the FDA in the United States).
How Should You Store Avodart?
Store Avodart at or below 30°C (86°F). Keep the capsules in their original packaging and out of the reach of children. Do not use the capsules after the expiration date printed on the carton. Do not dispose of unused medicines in drains or household waste – return them to a pharmacy for safe disposal.
Proper storage of medication is essential to maintain its safety and effectiveness. Avodart soft capsules contain a liquid formulation of dutasteride and should be stored under conditions that prevent degradation of the active ingredient and the capsule shell.
- Temperature: Store at or below 30°C (86°F). Avoid exposure to excessive heat.
- Light and moisture: Keep the capsules in the original blister packaging until use to protect from light and moisture.
- Children: Store out of sight and reach of children. The soft capsules may be attractive to young children and could pose a choking hazard.
- Expiration date: Do not use Avodart after the expiration date shown on the carton and blister strips. The expiration date refers to the last day of that month.
- Disposal: Do not throw unused medicines into drains or household waste. Ask your pharmacist how to dispose of medications that are no longer needed. These measures help protect the environment.
If you notice that a capsule appears damaged, leaking, or discolored, do not take it. Leaking capsules are a particular concern because the contents can be absorbed through the skin and may harm a developing male fetus if handled by a pregnant woman. Dispose of damaged capsules safely and keep them away from women and children.
What Does Avodart Contain?
Each Avodart soft capsule contains 0.5 mg of dutasteride as the active ingredient. The capsule also contains excipients including mono- and diglycerides of caprylic/capric acid, butylated hydroxytoluene (E321), gelatin, glycerol, titanium dioxide (E171), yellow iron oxide (E172), medium-chain triglycerides, and lecithin (which may contain soy oil).
Understanding what your medication contains is important, particularly if you have known allergies or intolerances to specific substances. Each component of Avodart serves a specific purpose in the formulation.
Active Ingredient
The active ingredient is dutasteride, present at a dose of 0.5 mg per soft capsule. Dutasteride is a synthetic 4-azasteroid compound that acts as a dual inhibitor of both type 1 and type 2 5-alpha reductase enzymes, responsible for the conversion of testosterone to the more potent androgen dihydrotestosterone (DHT).
Inactive Ingredients (Excipients)
The capsule contains the following excipients:
- Capsule fill: Mono- and diglycerides of caprylic/capric acid (medium-chain triglycerides) and butylated hydroxytoluene (E321, an antioxidant)
- Capsule shell: Gelatin, glycerol, titanium dioxide (E171, a whitening agent), yellow iron oxide (E172, for color), medium-chain triglycerides, and lecithin (which may contain soy oil)
Avodart capsules contain lecithin derived from soy, which may contain soy oil. If you are allergic to peanuts or soy, do not take this medicine. Inform your doctor about your allergy so that a suitable alternative treatment can be arranged.
Capsule Appearance
Avodart soft capsules are oblong, opaque, yellow, soft gelatin capsules marked with "GX CE2." They are supplied in blister packs of 10, 30, 50, 60, or 90 capsules, although not all pack sizes may be available in every country.
Frequently Asked Questions About Avodart
References and Sources
This article is based on peer-reviewed medical literature, international clinical guidelines, and approved product information. All medical claims are supported by Level 1A evidence (systematic reviews and meta-analyses of randomized controlled trials) where available.
- European Medicines Agency (EMA). Avodart (dutasteride) – Summary of Product Characteristics (SmPC). Last updated 2025. Available from: www.ema.europa.eu
- Roehrborn CG, Siami P, Barkin J, et al. The effects of combination therapy with dutasteride and tamsulosin on clinical outcomes in men with symptomatic benign prostatic hyperplasia: 4-year results from the CombAT study. European Urology. 2010;57(1):123–131. doi:10.1016/j.eururo.2009.09.035
- Andriole GL, Bostwick DG, Brawley OW, et al. Effect of dutasteride on the risk of prostate cancer (REDUCE trial). New England Journal of Medicine. 2010;362(13):1192–1202. doi:10.1056/NEJMoa0908127
- European Association of Urology (EAU). Guidelines on the Management of Non-neurogenic Male Lower Urinary Tract Symptoms (LUTS), including Benign Prostatic Obstruction (BPO). 2024 edition.
- American Urological Association (AUA). Surgical Management of Lower Urinary Tract Symptoms Attributed to Benign Prostatic Hyperplasia: AUA Guideline. 2023.
- British National Formulary (BNF). Dutasteride. National Institute for Health and Care Excellence (NICE). Available from: bnf.nice.org.uk
- World Health Organization (WHO). WHO Model List of Essential Medicines. 23rd edition, 2023.
- U.S. Food and Drug Administration (FDA). Avodart (dutasteride) Prescribing Information. GlaxoSmithKline. Reference ID: 4932640.
- Nickel JC, Gilling P, Tammela TL, et al. Comparison of dutasteride and finasteride for treating benign prostatic hyperplasia: the Enlarged Prostate International Comparator Study (EPICS). BJU International. 2011;108(3):388–394. doi:10.1111/j.1464-410X.2011.10195.x
- Traish AM, Hassani J, Guay AT, Zitzmann M, Hansen ML. Adverse side effects of 5α-reductase inhibitors therapy: persistent diminished libido and erectile dysfunction and depression in a subset of patients. Journal of Sexual Medicine. 2011;8(3):872–884. doi:10.1111/j.1743-6109.2010.02157.x
About the Medical Editorial Team
This article has been written and reviewed by the iMedic Medical Editorial Team, consisting of licensed physicians specializing in urology, clinical pharmacology, and evidence-based medicine. Our team follows the GRADE framework for evaluating the quality of evidence and strength of recommendations.
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