Finasteride (1 mg & 5 mg): Uses, Dosage, Side Effects & Safety

Finasteride is a prescription medicine used to treat male pattern hair loss (androgenetic alopecia) and benign prostatic hyperplasia (BPH)—an enlarged prostate. It helps slow or stop hair loss and may regrow hair at the crown in adult men, and it shrinks the prostate to improve urinary symptoms in BPH. It is not approved for use in women or children and must be handled with care by people who are or may become pregnant.

In this clear, patient-friendly guide, you’ll learn what finasteride is, how it works, when doctors prescribe it, how to take it, what to expect, possible side effects, safety tips (including PSA testing and pregnancy handling precautions), and answers to the most-searched questions.

Quick disclaimer: This article is for education only and not a substitute for professional medical advice. Always follow your prescriber’s instructions. Seek urgent care for severe reactions or mental-health concerns.

What Is Finasteride?

Finasteride is a 5-alpha-reductase inhibitor. It blocks the conversion of testosterone to dihydrotestosterone (DHT)—a hormone that contributes to hair follicle miniaturization on the scalp and prostate growth in the lower urinary tract.

Common forms & strengths (region/brand may vary):

• Tablets, 1 mg — typically used for male pattern hair loss
• Tablets, 5 mg — used for benign prostatic hyperplasia (BPH)
• Topical finasteride (sprays/solutions/foams) — compounded/off-label in some countries; talk to your clinician about evidence, dosing, and safety

How Does Finasteride Work?

• Blocks type II 5-alpha-reductase, lowering scalp and prostate DHT levels.
• Hair loss: Reduced DHT helps halt follicle miniaturization, allowing thicker hair growth cycles.
• BPH: Lower DHT shrinks prostate tissue over time, improving urine flow, nocturia, and urinary frequency.
• Because hair growth cycles take time, results are gradual and require continued daily use to maintain benefits.

Common Uses of Finasteride

1. Male Pattern Hair Loss (Androgenetic Alopecia)
   • Adult men with thinning at the crown and/or receding hairline.
   • Can be used alone or with topical minoxidil; some men also use low-level laser devices or microneedling under professional guidance.
2. Benign Prostatic Hyperplasia (BPH)
   • Adult men with enlarged prostate and bothersome urinary symptoms (weak stream, hesitancy, frequency, nocturia).
   • May be used alone or with an alpha-blocker (e.g., tamsulosin) when faster symptom relief is needed.

Not approved for women or children. People who are or may become pregnant must not take finasteride and should not handle crushed/broken tablets.

Finasteride Dosage & Administration

Your clinician will tailor the dose for your condition and health history.

Hair loss (men):

• 1 mg by mouth once daily (with or without food), same time each day.
• Expect 3–6 months to notice less shedding or early regrowth; 12 months for full assessment.

BPH (men):

• 5 mg by mouth once daily (with or without food).
• Symptom improvement can begin within several weeks; maximum benefit may take 6 months or longer.
• Often continued long-term to maintain prostate size reduction and lower risk of acute urinary retention or BPH surgery.

Special situations & practical tips

• Missed dose: Take when remembered unless near the next dose; don’t double.
• PSA testing: Finasteride can reduce PSA by ~50% after ~6 months. Tell your clinician/lab you take finasteride so results can be interpreted correctly.
• Handling precautions: Do not crush or split tablets. People who are or may become pregnant should avoid contact with crushed/broken tablets.
• Stopping therapy: Hair benefits reverse within months after stopping; BPH symptoms may gradually return.

Side Effects of Finasteride

Most people tolerate finasteride well. Some side effects are dose-related and may improve with time. Report persistent or distressing symptoms to your clinician.

Common (usually mild):

• Decreased libido, erectile dysfunction, reduced ejaculate volume
• Breast tenderness or enlargement
• Rash, itching
• Dizziness or weakness

Less common but important—seek medical advice:

• Mood changes, depression, anxiety; rare reports of suicidal thoughts
• Persistent sexual side effects after stopping have been reported in some men—discuss risks/benefits with your prescriber
• Breast lumps/pain or nipple discharge (rare male breast cancer has been reported; get evaluated)
• Testicular pain

Allergic reactions (swelling of lips/face, difficulty breathing) are rare but require urgent care.

Warnings & Precautions

• Pregnancy risk: Finasteride can cause birth defects in a male fetus. It is contraindicated in pregnancy and not for women. Avoid handling broken tablets.
• PSA & prostate cancer screening: Finasteride lowers PSA; clinicians typically adjust interpretation (often doubling measured value). 5-alpha-reductase inhibitors have been associated with a reduced overall risk of prostate cancer but a higher proportion of high-grade cancers in some analyses—discuss screening with your clinician.
• Liver disease: Use with caution; tell your prescriber if you have liver problems.
• Blood donation: Many blood centers advise no donation while taking finasteride and for at least 1 month after the last dose.
• Fertility: Changes in sperm parameters have been reported (usually reversible). If you’re trying to conceive, discuss timing and options with your clinician.
• Adolescents/children: Not indicated.

Drug & Product Interactions

Finasteride has few clinically significant drug interactions.

• CYP3A4 metabolism: No routine dose changes are needed with common CYP3A4 modulators, but always share your full medication list.
• Alpha-blockers (e.g., tamsulosin) for BPH: Often combined for better symptom control; your clinician will monitor blood pressure and side effects.
• Topical minoxidil for hair: Safe to use together; many men benefit from dual therapy.
• Herbal products (e.g., saw palmetto): May also affect DHT; avoid stacking without professional advice.

Finasteride vs. Other Treatments

• Finasteride vs. Minoxidil (topical/oral):
  • Finasteride lowers DHT to address hormonal cause; best for crown density.
  • Minoxidil increases follicle blood flow/growth signals; works across the scalp.
  • Together they often perform better than either alone.
• Finasteride vs. Dutasteride:
  • Dutasteride inhibits type I & II 5-alpha-reductase and may be more potent, but with potential for more side effects; hair-loss use is off-label in many regions.
• BPH options:
  • Alpha-blockers (tamsulosin, alfuzosin) relax prostate/bladder neck for quick relief, but don’t shrink the gland.
  • Finasteride/5-ARIs shrink the prostate and reduce long-term complications.
  • Combination therapy is common for moderate-to-severe symptoms or very enlarged prostates.
• Procedures for hair (PRP, transplant) and BPH surgeries (TURP, laser) are options when medicines are insufficient.

Cost & OTC Status

• Status: Finasteride is prescription-only in most countries.
• Cost: Widely available as generic; monthly cost is generally affordable, especially with discount programs or insurance for BPH.
• Access: Online telehealth services exist in many regions; ensure you use licensed providers and receive appropriate screening and follow-up.

Special Section: 1 mg vs. 5 mg vs. Topical (Off-Label)

• 1 mg tablet (hair loss):
  • Designed for scalp DHT reduction with a lower dose to limit systemic effects.
  • Best for adult men with early-to-moderate thinning; evaluate after 12 months.
• 5 mg tablet (BPH):
  • Targets prostate shrinkage and long-term symptom reduction; slows complications.
  • Not a hair-loss dose; do not take 5 mg for hair unless specifically directed.
• Topical finasteride (off-label):
  • Compounded solutions/foams aim for local scalp action with lower blood levels.
  • Emerging evidence suggests benefit, often combined with topical minoxidil; quality and dosing vary. Discuss risks, pregnancy precautions, and monitoring with a clinician.

Proper Care With Finasteride

Before starting

• Share your full medical history, all medicines, supplements, and mental-health background.
• Plan your PSA testing schedule if you’re on BPH therapy or undergoing prostate cancer screening.
• If your household includes someone who is or may become pregnant, store tablets securely; avoid handling broken/crushed tablets.

During treatment

• Take daily, same time, with or without food.
• Expect a gradual timeline (months) for results; set reminders to stay consistent.
• Report sexual, mood, or breast changes promptly.
• Keep all follow-ups for symptom checks, side-effect review, and lab tests (including PSA for BPH patients).

When to call urgently

• Swelling of lips/face, trouble breathing, or hives
• New or worsening depression, anxiety, or suicidal thoughts
• Breast lumps, nipple discharge, or severe chest pain

Frequently Asked Questions (FAQs)

1) How long before I see hair results?
Most men notice reduced shedding by 3 months and thicker coverage by 6–12 months. Keep taking it to maintain gains.

2) Will I shed at first?
Some men notice temporary shedding as follicles reset to a healthier growth cycle. This usually settles within a few weeks.

3) What happens if I stop finasteride?
Hair benefits typically fade within months; BPH symptoms may gradually return. Discuss any plan to stop with your prescriber.

4) Can I combine finasteride with minoxidil?
Yes—many clinicians recommend combination therapy for stronger results on hair.

5) Is finasteride safe long-term?
Many men take it for years under medical supervision. Regular check-ins help track benefits, side effects, mood, sexual health, and PSA (for BPH).

6) Does finasteride affect fertility?
Changes in sperm count/quality have been reported (often reversible). If you’re trying to conceive, discuss timing and alternatives.

7) Can women use finasteride?
It is not approved for women and is contraindicated in pregnancy due to risk of male fetal harm. Some specialists may consider off-label topical use in carefully selected post-menopausal women—this requires specialist care.

8) Do I need lab monitoring?
For hair loss alone, routine labs aren’t always needed. For BPH, clinicians monitor symptoms, PSA, and prostate size over time.

9) Does finasteride change PSA tests?
Yes. After ~6 months, PSA may drop by about 50%. Tell your clinician so results can be interpreted correctly.

10) Are sexual side effects permanent?
Most improve with time or after stopping, but persistent symptoms have been reported. Report issues early to review options.

11) Is “post-finasteride syndrome” real?
Some patients report persistent sexual, neurological, or physical symptoms after stopping. Research is ongoing. Discuss risks, screening, and alternatives with your clinician.

12) Can I drink alcohol while taking finasteride?
There’s no direct interaction, but use moderation and watch for dizziness or fatigue.

Final Thoughts

Finasteride is a well-studied option for two common male conditions: pattern hair loss and BPH. Its benefits come with clear rules for safe use—consistent dosing, patience with timelines, attention to mood and sexual health, and proper PSA interpretation. Partner closely with your clinician, use trusted pharmacies, and combine medication with good hair-care or BPH self-care strategies. That’s how you get the most from finasteride—safely and effectively.