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At a Glance
- Short answer There’s no reliable “start working” point, because in the best trials saw palmetto didn’t beat placebo for prostate symptoms at 3–6 months or at 12–17 months1.
- What trials timed STEP ran 1 year2; CAMUS raised the dose at 24 and 48 weeks and measured at 72 weeks3.
- Hair loss Changes were measured at 16 weeks to 6 months, and up to 2 years456.
- When to stop If nothing changes after about 3 months, it’s unlikely to help; see a doctor about other options.
- Top pick NOW Saw Palmetto Extract 320 mg – 320 mg of extract standardized to 85–95% fatty acids, the dose used in most trials, from our guide to the best pumpkin seed oil with saw palmetto supplements.
The Short Answer: For prostate symptoms, there’s no evidence-based timeline for saw palmetto to “kick in.” The 2023 Cochrane review found little to no difference from placebo after 3–6 months or after 12–17 months1. Two long US trials, lasting 1 year and 72 weeks, also found no benefit over placebo23.
On this page
If you try it, judge it after about 3 months. If your symptoms haven’t improved, more time is unlikely to help. Compare products in our guide to the best pumpkin seed oil with saw palmetto supplements.
Saw Palmetto Timeline From Clinical Trials
| Time point | Study | What happened |
|---|---|---|
| 3–6 months | Cochrane review 20231 | Little to no difference vs placebo in symptoms or quality of life |
| 12 months | STEP trial2 | No difference vs placebo in symptoms, urine flow or prostate size |
| 12–17 months | Cochrane review 20231 | Little to no difference vs placebo |
| 24, 48 and 72 weeks | CAMUS trial3 | Dose raised from 320 to 640 to 960 mg; no better than placebo at 72 weeks |
| 1 year or more | Permixon analysis 20187 | Results in long-term users were similar to the shorter studies of this one hexane extract |
Why Some People Feel Better Anyway
Urinary symptoms often improve on placebo too. In CAMUS, men on placebo improved by almost 3 points over 72 weeks, slightly more than men on saw palmetto3. That’s why personal experience can be misleading, and why trials compare against placebo.
Does a Different Extract Work Faster?
A 2018 meta-analysis of one hexane extract, Permixon, found fewer night-time bathroom trips and better urine flow than placebo, with similar results in men treated for a year or longer7. But it included observational studies and only that brand, and Cochrane found no difference between hexane and other extracts8. For more, see saw palmetto for BPH.
Our Top Saw Palmetto Pick
NOW Saw Palmetto Extract 320 mg
320 mg extract85–95% fatty acids1 softgel a day
If you want to run a 3-month trial, use the studied dose. NOW gives 320 mg of extract standardized to 85–95% fatty acids, the daily dose used in most trials, in one softgel. It’s the best standardized extract in our guide to the best pumpkin seed oil with saw palmetto supplements.
How Long Saw Palmetto Takes for Hair Loss
Hair studies measured results over longer periods:
- 16 weeks: A standardized saw palmetto oil reduced hair fall and raised density compared with placebo4.
- 6 months: A branded extract increased hair counts compared with placebo5.
- 2 years: 38% of men improved on saw palmetto, vs 68% on finasteride6.
Plan on 4–6 months before judging. See our full guide to saw palmetto for hair loss.
A Practical Approach
- See a doctor first to rule out other causes of urinary symptoms.
- Use the studied dose: 320 mg a day23. Higher doses didn’t help more3.
- Track your symptoms before you start and after 3 months, for example how often you wake at night to urinate.
- Stop if nothing changes after 3 months and talk to your doctor about other options, such as those in our guide to saw palmetto vs finasteride.
For a different supplement option, see pumpkin seed oil for prostate health.
When to See a Doctor Right Away
Don’t wait on a supplement if you can’t pass urine, see blood in your urine, or have fever, pain or sudden worsening symptoms. Urinary symptoms can also be caused by infection, bladder problems or prostate cancer. Saw palmetto doesn’t appear to change PSA readings8, but tell your doctor you take it.
Final Verdict
Saw palmetto doesn’t have a proven timeline for prostate symptoms because the best trials found it worked about as well as placebo, whether at 3 months or after more than a year123. If you try it, give it about 3 months, track your symptoms, and stop if nothing changes.
If you decide to try it, use the studied 320 mg dose, such as NOW Saw Palmetto Extract 320 mg. For side effects, see saw palmetto side effects, and for other uses, saw palmetto benefits.
Important: This guide is for general information and isn’t medical advice. Get urinary symptoms checked by a doctor before using saw palmetto.
Frequently Asked Questions
How long does saw palmetto take to work for the prostate?
How long does saw palmetto take to work for hair loss?
Does saw palmetto work better if I take more?
No. In CAMUS, raising the dose to 960 mg a day didn’t help more than placebo3.
Should I keep taking saw palmetto if it’s not working?
If nothing has changed after about 3 months, it’s unlikely to help. Talk to your doctor about other options.
Is it safe to take saw palmetto long term?
It has been used safely in studies for up to 3 years8.
Sources & History
References
- Serenoa repens for the Treatment of Lower Urinary Tract Symptoms Due to Benign Prostatic Enlargement — Cochrane Database of Systematic Reviews, 2023
- Saw Palmetto for Benign Prostatic Hyperplasia — New England Journal of Medicine, 2006
- Effect of Increasing Doses of Saw Palmetto Extract on Lower Urinary Tract Symptoms: A Randomized Trial — JAMA, 2011
- Oral and Topical Administration of a Standardized Saw Palmetto Oil Reduces Hair Fall and Improves the Hair Growth in Androgenetic Alopecia Subjects: A 16-Week Randomized, Placebo-Controlled Study — Clinical, Cosmetic and Investigational Dermatology, 2023
- The Safety and Efficacy of a Novel Saw Palmetto (Serenoa repens) Extract for Promoting Hair Growth in Adults With Self-Perceived Thinning Hair: 180-Day Results — Journal of Cosmetic Dermatology, 2026
- Comparative Effectiveness of Finasteride vs Serenoa repens in Male Androgenetic Alopecia: A Two-Year Study — International Journal of Immunopathology and Pharmacology, 2012
- Efficacy and Safety of a Hexanic Extract of Serenoa repens (Permixon) for the Treatment of Lower Urinary Tract Symptoms Associated With Benign Prostatic Hyperplasia: Systematic Review and Meta-Analysis — BJU International, 2018
- Saw Palmetto: Usefulness and Safety — National Center for Complementary and Integrative Health
Update history
- Rewritten with a timeline table from the Cochrane review and the STEP, CAMUS and Permixon studies, added hair loss timelines, and added sources (the previous version had none).
