Dutasteride vs Finasteride

May 29, 2025/Andrew Le

Looking for something that actually works for hair loss is very confusing because of the wide variety of drugs available. Dutasteride and finasteride are commonly used and both block DHT, the hormone behind shrinking hair follicles. 

So, is there a difference? In brief, both dutasteride and finasteride block enzymes responsible for DHT production, however dutasteride has a broadened effect, potentially lowering DHT levels further than finasteride. 

In this article, we break down the key points of dutasteride and finasteride, including mechanism of action, onset of effect, how well each medication works, side effects, and cost. This should help you make an informed decision of which drug might be most beneficial for you. 

🔑Key Takeaways

➤ Dutasteride blocks both type I and II 5α-reductase enzymes, cutting DHT levels by over 90%.

➤ Finasteride mainly blocks type II and lowers DHT by about 70%, it has a milder effect.

➤ Dutasteride is stronger but may cause more side effects.

➤ Finasteride is indicated for both BPH and hair loss, while Dutasteride is indicated only for BPH but is commonly used for hair loss treatment. 

➤ Dutasteride may take 6 months to work, while finasteride can show results in 3 to 12 months.

➤ Both drugs must be taken daily and long-term to keep their benefits.

➤ Finasteride is cheaper than dutasteride, especially when bought from Cost Plus.

➤ Women who are or may become pregnant should avoid handling either drug due to possible harm to a male fetus.

Mechanism of Action

Dutasteride blocks both type I and II 5α-reductase enzymes to cut DHT by over 90%, while finasteride targets mainly type II and lowers DHT by about 70%.

Dutasteride 

According to a study, Dutasteride is a potent and irreversible dual inhibitor of the enzyme 5α-reductase, specifically targeting both type I and type II isoenzymes. These enzymes are responsible for converting testosterone into dihydrotestosterone (DHT), a more potent androgen that plays a key role in male pattern hair loss.

Finasteride

According to a study, Finasteride works by competitively inhibiting the type II and III isoenzymes of 5α-reductase, which convert testosterone into DHT. Unlike dutasteride, finasteride has minimal effect on type I 5α-reductase, so its overall suppression of DHT is less complete.

Type II is found in the prostate, hair follicles, epididymis, vas deferens, and seminal vesicles. Type III is less well understood but also contributes to androgen metabolism. Finasteride targets these to reduce the levels of DHT in tissues where it drives growth and activity.

Dosage and Administration 

Dutasteride and finasteride are taken once a day, but while dutasteride is used mainly for BPH, finasteride treats both BPH and hair loss, with different doses and similar safety rules.

Dutasteride 

Dutasteride’s standard adult dose is 0.5 mg taken orally once a day. You can take it with or without food. Don’t chew or open the capsules, swallow them whole. This is important because the contents may irritate your mouth or throat.

No dose adjustments are needed if you have kidney problems. But for people with liver impairment, caution is advised. Dutasteride is heavily processed in the liver, so drug levels might rise. 

Women, especially those who are pregnant should not handle leaking capsules. Dutasteride can be absorbed through the skin and may harm a male fetus. If contact happens, the area should be washed with soap and water immediately.

Finasteride 

For male pattern hair loss, the dose of Finasteride is 1 mg daily. Like dutasteride, it can be taken with or without meals and should be taken around the same time each day to keep drug levels steady.

You should swallow the tablet whole. This avoids unwanted skin contact, especially important for women who are or may become pregnant.

There’s no need to adjust the dose in kidney disease. But if you have liver problems, your doctor may monitor you more closely, since the drug is processed by the liver.

Treatment needs consistency. It can take 3 months or longer to see improvement in hair growth. Stopping the drug reverses the effects such as hair loss may return, and urinary symptoms could worsen.

If you miss a dose, take it as soon as you remember, but skip it if it’s been more than 6 hours. While overdoses are unlikely to be dangerous, you should still get medical advice if you feel unwell after taking too much.

DutasterideFinasteride
IndicationsBenign Prostatic Hyperplasia (BPH)BPH (5 mg), Male Pattern Hair Loss (1 mg)
Standard Dose0.5 mg orally once daily5 mg once daily for BPH; 1 mg once daily for hair loss
With/Without FoodCan be taken with or without foodCan be taken with or without food
Tablet/Capsule HandlingSwallow capsule whole; do not chew or openSwallow tablet whole; do not crush or break
Dose AdjustmentsNo renal adjustment; caution in liver impairmentNo renal adjustment; caution in liver impairment
Special PrecautionsAvoid capsule contact in pregnancy; long half-life (5 weeks)Avoid tablet contact in pregnancy; reversible if stopped

Onset of Effect and Duration 

Dutasteride starts working in about 6 months, while finasteride may show results in 3 to 12 months, but both need long-term use to keep the hair growth.

Dutasteride

According to a study, dutasteride at a dose of 0.5 mg per day starts to show noticeable improvement in hair growth by week 24. This was demonstrated in men aged 20 to 50 with androgenetic alopecia. Compared to both placebo and finasteride, dutasteride produced a significant increase in hair count by this time point. 

The findings confirm that while dutasteride does not work instantly, visible benefits appear after about 6 months of continuous treatment. 

Also, because dutasteride has a long half-life of 5 weeks, as found in one study, the drug stays in your system for months even after stopping, helping to maintain its effects for a while. However, sustained use is still needed to keep the results.

Finasteride

Experts say that oral finasteride (1 mg daily) also requires at least 3 months before any hair regrowth becomes visible. That said, many men may not see full results until after 6 to 12 months. 

In fact, a 2-year study showed hair growth improvement in 48% of men at 1 year, and in 66% at 2 years. Moreover, 83% of users had no further hair loss after 2 years compared to only 28% in the placebo group. Still, like dutasteride, the benefit only continues as long as the drug is taken. Once stopped, the new hair will typically shed within a year.

DrugOnset of EffectDuration of Use for Results
DutasterideAround 6 months (week 24)Long-term use is required to maintain hair growth
FinasterideAt least 3 months; more results by 6–12 monthsContinuous use is needed; hair sheds within a year if stopped

Efficacy 

Dutasteride is more effective than finasteride in boosting hair growth, but both drugs work best with consistent, long-term use.

Dutasteride

According to a multicenter retrospective study involving 600 men with androgenetic alopecia (AGA), oral dutasteride at 0.5 mg per day was found to be more effective than finasteride at 1 mg per day in improving hair growth. Patients treated with dutasteride showed greater improvements based on the BASP basic M classification compared to other medications. 

In another randomized, placebo-controlled trial, dutasteride 0.5 mg daily significantly increased both hair count and hair shaft width in a 2.54 cm area of the scalp. Compared to finasteride, dutasteride showed stronger results in hair growth by week 24, with p-values of .003 for hair count, .004 for width, and .002 for photographic assessment. These results were also superior to placebo. 

Additionally, a Korean 5-year observational study involving 99 men treated with 0.5 mg dutasteride found that 89.9% experienced visible improvement, and 93.9% showed either improvement or prevention of further hair loss. BASP classification also improved, with 52.5% improvement in basic type, 75% in specific F type, and 83.3% in specific V type patterns.

Topical dutasteride has also been tested. A 2022 double-blind, randomized study combined microneedling with a 0.01% topical dutasteride solution. By week 16, 52.9% of men in this group showed significant improvement compared to 17.6% in the saline-only group. However, topical dutasteride alone has not shown strong efficacy unless combined with methods like microneedling.

Finally, a retrospective analysis used intradermal injectable dutasteride at 0.1%. Hair density and width improved after regular injections every three months. 

Finasteride 

According to phase III clinical studies involving 1,879 men, daily use of oral finasteride 1 mg significantly improved hair growth and reduced further loss. After 1 year, 48% of users saw visible improvement in global photographs of the vertex scalp. This increased to 66% after 2 years. Hair count results showed that 83% of men on finasteride maintained their baseline hair count compared to only 28% of those on placebo.

A 24-month multicenter, double-blind study with 424 men (aged 41 to 60) also confirmed the benefits. Finasteride significantly improved scalp hair growth starting at month 6 and sustained gains through month 24. Patient and investigator assessments matched the photographic data. These results confirm that finasteride works best with long-term, consistent use.

Another Japanese study involving 37 men found that 59.5% of all patients had good or excellent response to finasteride. Among those with more body hair (Group A), the success rate was higher at 88.9%. For those with less body hair (Group B), only 31.6% responded well.

Three long-term investigations reported that more than 87% of patients showed major improvement, and over 99% had some degree of improvement. These studies noted better outcomes in men younger than 40 and those in early stages of AGA. Also, these studies found a very low incidence of adverse reactions over time 0.7% in 2.5 years and 6.8% in 10 years with no reported cases of post-finasteride syndrome.

Lastly, another 5-year study found that 65% of men with mild-to-moderate AGA had a positive response to finasteride. However, treatment needs to be continuous to keep results. Some doctors also pair finasteride with minoxidil or surgical treatments for better long-term outcomes.

Side Effects 

Dutasteride and finasteride can both cause sexual side effects, but dutasteride may lead to more serious reactions like chest pain or severe allergic responses.

Dutasteride 

Dutasteride is generally well-tolerated, but it can cause a range of side effects. Some are rare but serious, while others are more common and often mild.

Serious side effects:

  • Chest pain or discomfort
  • Dilated neck veins
  • Extreme fatigue
  • Irregular heartbeat or breathing
  • Swelling of the face, fingers, feet, or lower legs
  • Rapid weight gain
  • Trouble breathing
  • Blistering, peeling, or flaking of the skin
  • Hives or welts, itching skin, or rash
  • Large swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or genitals
  • Tightness in the chest
  • Unusual tiredness or weakness

Less serious side effects:

  • Abnormal ejaculation
  • Decreased libido
  • Erectile dysfunction
  • Reduced sexual performance
  • Pain, soreness, or swelling of the breast area
  • Breast discharge
  • Allergic reactions (rash, swelling of the face, tongue, or throat)
  • Breast lumps or discharge

Finasteride

Finasteride has some overlap in side effects with dutasteride but also comes with its own risks. Serious side effects are rare but can be severe.

More common side effects:

  • Decreased sexual desire
  • Difficulty getting or maintaining an erection
  • Decreased semen volume
  • Reduced sexual performance

Less common or rare side effects:

  • Breast enlargement or tenderness
  • Skin rash or hives
  • Rapid weight gain
  • Red or swollen skin
  • Tingling in hands or feet
  • Diarrhea
  • Headache
  • Back pain
  • Stomach pain
  • Drowsiness
  • Runny or stuffy nose

Serious and rare side effects:

  • Lumps or pain in the chest area
  • Nipple discharge or changes in breast appearance
  • Mood changes, including depression
  • Testicular pain
  • Signs of a serious allergic reaction (swollen lips, difficulty breathing, rash with blistering or peeling)

Cost

Finasteride costs less than dutasteride, but both are much cheaper through Cost Plus compared to regular pharmacy prices.

Dutasteride 

A 30-count supply of 0.5 mg dutasteride capsules costs $7.61. This price includes a breakdown of $2.27 for manufacturing, $0.34 for a 15% markup, and $5.00 for pharmacy labor. But keep in mind, shipping and taxes are not yet added. 

Finasteride

A 30-count supply of 1 mg finasteride tablets costs $5.82. That includes $0.72 for manufacturing, a 15% markup of $0.11, and the same $5.00 pharmacy labor fee. Like dutasteride, the standard shipping is $5.00, and local taxes apply at checkout.

MedicationDosage & Form30-Count Base PriceEstimated Final Cost (with shipping)
Dutasteride0.5 mg capsule$7.61$12.61 (plus tax)
Finasteride1 mg tablet$5.82$10.82 (plus tax)

Wrap Up

Dutasteride and finasteride both reduce DHT, but they work differently in doing so. 

Dutasteride blocks more enzyme types, so it cuts DHT more deeply. That gives it stronger effects, especially for hair growth. But it may also come with a higher risk of side effects and stays in your system longer. 

Finasteride, on the other hand, acts more selectively and clears from your body faster. It’s also cheaper and widely used for both BPH and hair loss. 

Your choice depends on what you need, more power or fewer risks, faster clearance or longer action. Always talk to your doctor to match the drug to your condition, goals, and health background.

FAQs About Dutasteride vs Finasteride

Is it safe to stop dutasteride or finasteride abruptly? 

Yes, but the benefits wear off. 

Can either drug affect fertility long-term? 

Yes. Dutasteride can lower semen volume and sperm motility, and these effects may persist. Finasteride may temporarily reduce sperm quality, especially at 5 mg doses

How long should you wait to donate blood after stopping these drugs? 

The FDA and Mayo Clinic advise waiting at least 6 months after your last dutasteride dose to avoid harming pregnant recipients.

Do dutasteride or finasteride affect PSA test results? 

Yes. Both lower PSA (prostate-specific antigen) levels by about 50%, which can mask prostate cancer. Doctors must adjust the interpretation of PSA tests accordingly.

Sources

  • Gubelin Harcha, W., Barboza Martínez, J., Tsai, T. F., Katsuoka, K., Kawashima, M., Tsuboi, R., Barnes, A., Ferron-Brady, G., & Chetty, D. (2014). A randomized, active- and placebo-controlled study of the efficacy and safety of different doses of dutasteride versus placebo and finasteride in the treatment of male subjects with androgenetic alopecia. Journal of the American Academy of Dermatology, 70(3), 489–498.e3. https://doi.org/10.1016/j.jaad.2013.10.049. Retrieved from https://pubmed.ncbi.nlm.nih.gov/24411083
  • Lim, J. H., Choi, S. M., Kwon, S. H., Sim, W. Y., & Lew, B. L. (2023). Long-term efficacy and safety of dutasteride in Korean men with androgenetic alopecia: 5-year follow-up data exhibiting clinical improvement with sustained efficacy. Journal of the American Academy of Dermatology, 89(3 Suppl), AB189. Retrieved from https://www.jaad.org/article/S0190-9622(23)01684-2/fulltext
  • Nohria, A., Desai, D., Páez-García, M. S., Lo Sicco, K. I., & Shapiro, J. (2024). Outcomes of androgenetic alopecia treated with dutasteride mesotherapy: A case series. JAAD Case Reports, 54, 53–58. https://doi.org/10.1016/j.jdcr.2023.08.004
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