Key takeaways
- Men's frown muscles tend to be bulkier, and on the approved 20-unit dose fewer men than women reached a good result.
- Dose comparison: In a trial of 80 men given 20, 40, 60, or 80 units, 40 units and above worked better and lasted longer than 20 units.
- The effect usually starts 1 to 2 days after injection, builds over the first week, and lasts about 3 to 4 months.
- When to judge: Don't decide it "didn't work" in the first week; check a full frown at around day 30.
For many men, 20 units in the frown area doesn't relax the "11 lines" as fully as it does for women. In the FDA-approved label's glabellar trials, 85% of women but only 59% of men had no or mild frown lines at day 30 on the same 20-unit dose. Men's frown muscles tend to be larger, so the muscle itself, not just the product, often explains why a standard dose feels weak.
Why Does the Same Dose Feel Weaker in Men?
Why Does the Same Dose Feel Weaker in Men?
It's mostly about muscle size. The frown area is driven by the corrugator muscles, which pull the inner brows together, and the procerus, which pulls the skin between the brows downward. These are among the larger muscles treated with botulinum toxin in the face, and men typically have more muscle mass here than women. That's why a 2012 review recommended judging each person's muscle mass and adjusting both the dose and the number of injection points.
Why Does the Same Dose Feel Weaker in Men?
Patients' own ratings pointed the same way: 93% of women and 72% of men felt their frown lines had improved. Keep in mind that 82% of trial participants were women, and the split by sex was an exploratory look rather than a planned comparison. So it doesn't mean the treatment fails in men. It means that at the same dose, more men were left with lines that hadn't relaxed enough.
Units: A measure of the toxin's strength. Each product is measured differently, so units from one product can't be compared with or converted to another's.
Do Men Get Better Results With a Higher Dose?
Do Men Get Better Results With a Higher Dose?
In a men-only dose study, 40 units or more relaxed frown lines better than 20 units. Researchers randomly assigned 80 men to 20, 40, 60, or 80 units and checked them every month. As the dose went up, so did the share of men whose lines faded at a full frown and the number of months the effect held. Side effects didn't increase at the higher doses, and the authors concluded men should start at 40 units or more.
Do Men Get Better Results With a Higher Dose?
That study has limits. It used one product, included only 80 men, and the abstract doesn't report participants' ethnic backgrounds, so the exact numbers may not carry over to every man. A 2024 overview of toxin treatment in men reached a similar point, noting that men often need about double the standard dose women receive for frown lines.
It's important to know that 40 units is above the FDA-approved glabellar dose of 20 units, which makes it an off-label use. If a higher dose is suggested, ask why that amount fits your muscles. Dose is just one part of the plan. Where the muscle bunches up most when you frown helps decide how the injections are spread out. Individual results vary.
Hasn't It Worked Yet, or Did It Wear Off Early?
Hasn't It Worked Yet, or Did It Wear Off Early?
The next morning is too early to tell. The effect typically kicks in 1 to 2 days after injection and gets stronger over the first week. That's why it makes sense to wait at least a week, and ideally to judge at around day 30, which is when the approval trials measured results.
| Time after injection | What's happening | What to check |
|---|---|---|
| Days 1–2 | Muscle starts to weaken | Don't judge yet |
| First week | Effect keeps building | Swelling, bruising, eyelid position |
| Around day 30 | When trials judged results | Photo of a full frown |
| 3–4 months | Usual length of effect | Date your frown came back |
Look at a hard frown, not a relaxed face. Both the label trials and the 80-man study rated lines at maximum frown, so that's the fair test. If your frown came back much sooner than 3 to 4 months, bring the units and number of injection points from last time to your next visit. A day-30 photo helps show whether the dose was low or your muscles were simply strong from the start. It also helps to take a frown photo before the injection in the same light.
What's Normal After Treatment, and When to Get Help?
What's Normal After Treatment, and When to Get Help?
Pain, swelling, redness, or bruising where the needle went in can happen with any injection. Side effects generally show up within the first week. In the glabellar trials, the most common side effect was a drooping eyelid, seen in 3% of 405 treated people. For men with bulkier brow muscles, the label specifically warns against injecting near the muscle that lifts the eyelid, so placement matters as much as dose.
These symptoms can appear hours, days, or weeks after an injection. If you notice any of them, call your doctor or get medical help right away:
- Trouble swallowing, speaking, or breathing
- Loss of strength and muscle weakness all over the body
- Double vision, blurred vision, or drooping eyelids
- Hoarseness or a change in or loss of voice
- Trouble saying words clearly
- Loss of bladder control
- Wheezing, asthma symptoms, or feeling dizzy or faint
The FDA warns that swallowing and breathing problems can be life-threatening, and deaths have been reported. There hasn't been a confirmed serious case of the toxin spreading away from the injection site at the approved 20-unit frown-line dose, but that statement applies to the approved dose. Don't wait it out if any of these symptoms show up.
What Should You Ask at Your Next Appointment?
What Should You Ask at Your Next Appointment?
If your last treatment felt weak, the one question to bring is: "Looking at the size of my frown muscles, how many units would you use, and across how many points?" Hearing both numbers lets you compare this plan with your last one.
If you're in Seoul and want STON Clinic in Myeongdong to take a look, include the date and units of your last treatment if you know them, a full-frown photo from about 30 days after it, and roughly when the frown came back. If you're offered more than the approved dose, ask about the reasoning in the same conversation. And if you don't have records from last time, ask for the units and injection points to be written down this time so the next comparison is easy.
If this raised a question about your own skin
Ask a questionReferences
- Approved 20-unit frown line dose, results by sex, and spread warning — U.S. FDA, 2024 — U.S. Food and Drug Administration
- 80 men given 20, 40, 60, or 80 units for frown lines — Dermatol Surg, 2005 — PubMed Central
- Adjusting dose to frown muscle mass, a review — J Drugs Dermatol, 2012 — PubMed Central
- Overview of toxin treatment in men — Dermatol Surg, 2024 — PubMed Central
Frequently asked questions
Q. Should men start at 40 units for frown lines?
A. There's no single right number. The FDA-approved glabellar dose is 20 units for everyone, while the 80-man study concluded men should start at 40 units or more. Since muscle strength varies, it's best to have your frown assessed and hear the reason before going above the approved dose.
Q. Does a higher dose raise the risk of droopy brows or eyelids?
A. In the 80-man study, side effects didn't increase with the higher doses. That said, a study of 80 people can't rule out rare reactions. Drooping is tied to where the toxin goes as much as how much, so ask how the injections will stay clear of the eyelid area.
Q. If I also treat forehead lines, does the frown dose change?
A. Under the FDA label, forehead lines treated together with frown lines get 20 units each, for 40 units total. The forehead is meant to be treated along with the frown area to lower the chance of brow drooping. Since men's frown doses can differ, ask for the units in each area so you can compare next time.
Q. Can I tell on my own if my frown muscles are large?
A. It's hard to measure accurately at home. Researchers have built a validated scale that grades frown muscle mass, and the label says the dose should be based on watching how your muscles move when you frown. Bringing a photo of a full frown makes that conversation easier.
Q. If it wore off fast, can I get it again before 3 months?
A. The safety and effectiveness of treatment more often than every 3 months haven't been established. If it wore off quickly, it's usually more useful to rethink the units and injection points next time than to shorten the gap. Photos from day 30 and from the day your frown came back help with that decision.
Q. Is 20 units ever enough for men?
A. Yes. In the label trials, 59% of men given 20 units had no or mild frown lines at day 30. So instead of starting high by default, the dose can be matched to your muscle size and frown strength, then checked with a day-30 photo.
Jangju Kim Senior Director
JANGJU KIM
Dr. Jangju Kim is a clinic director at STON Clinic, LOTTE HOTEL in Myeongdong.
Career / Education
- 현) 스톤클리닉 명동 롯데호텔 원장
- 경희대학교 의과대학 졸업
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