Calf Botox relaxes the muscle 2 to 4 days after the injection, but the change in your leg line is judged at about 6 to 8 weeks. Calf size keeps shrinking slowly over the following months, so a second session is timed after 3 months, based on whether the calf muscle starts to bulge again.

That's why a mirror that looks the same at week 2 isn't a sign the treatment failed. Below, we walk through what changes first, how much the measurements actually move, what's normal when you walk, and how the second session is timed.

At a Glance

• Judge your first calf Botox result by the outline of your legs from behind, not by how they look in the first couple of weeks.

• When it starts: the muscle weakens within 2 to 4 days, while the line changes over several weeks.

• In studies, calf circumference shrank by about 0.5 cm at 8 weeks and by 0.67 cm at 6 months, so the change is modest.

• Second session: decided after 3 months, once the muscle starts getting its strength back.

How Soon Does Calf Botox Start Working?

Within 2 to 4 days, the muscle starts to lose some of its strength, and it's at its weakest around day 10. What you notice then is a feeling rather than a look. Your calf feels less hard when you rise up on your toes, while the outline in the mirror usually hasn't changed yet.

The line changes only after the muscle you're no longer using hard loses some of its bulk. That takes longer than smoothing a forehead line. Expression lines are checked at about 3 to 4 weeks, but for the calves, where the goal is muscle volume, the first real check comes at 6 to 8 weeks.

The injection goes into the gastrocnemius*, the rounded muscle at the upper back of your lower leg. Most of the visible bulge comes from its inner head, which is why the injection points are usually spread over that area.

*Gastrocnemius: the two-part muscle that forms the rounded bulge at the upper back of the calf. It's the muscle you feel tighten when you stand on tiptoe.

How Much Does Calf Size Shrink, and for How Long?

Don't expect your calves to lose several centimeters after one session. In a Korean trial of 20 people with both legs treated, average calf circumference went from 36.35 cm to 35.87 cm at 8 weeks.

A second study set the dose by each person's muscle thickness, using 100 to 300 units in 27 people, and measured the widest part of the calf over 6 months. Here's how the two compare:

Those are small numbers on a tape measure. What changes more is the shape: a bulging, angular calf tends to soften into a smoother line, even if the leg isn't much thinner overall. That's why a photo of your calves from behind tells you more than a measurement. Since the change at 6 months was bigger than at 3 months in that study, a small difference at weeks 2 to 3 doesn't mean it didn't work. How much you see depends on your muscle and your legs.

Does Calf Fat Change How Slim Your Legs Look?

Yes, the fat layer over the muscle affects how happy people are with the result. In a study of 50 people who all received 300 units, grouped by the thickness of the fat under the skin, satisfaction with the calf contour at 6 months was high in the very thin and the thick fat groups, and lower in the middle group. Satisfaction with how much the circumference changed was low in all three groups.

Botox works on muscle, not fat. If your calf feels mostly soft when you rise onto your toes, rather than showing a firm, rounded bulge, the change in outline may be smaller than you hoped. Results differ from person to person.

Your two calves also aren't always the same. Before the injection, the doctor looks at the balance of your whole leg and the difference between your left and right calves, then sets the dose and the injection points for each side.

Calf Botox Side Effects: What's Normal When You Walk?

Some weakness is the point of the treatment. If you walk normally but your calves feel heavy or don't push off as strongly, that's an expected effect, and it passes. Spread of the toxin beyond the injection area is rarely reported, but it can show up anywhere from hours to weeks after the injection.

What's usually fine to watch

• Small bruises and soreness at the injection points that fade a little more each day

• Walking on flat ground feels normal, but standing on tiptoe doesn't hold as long as before

Get medical care right away if you notice

• Trouble swallowing, breathing, or speaking

• Drooping eyelids or double vision

• Weakness throughout your body, not just in your legs

• An injection site that keeps getting redder, more swollen, and warm

If you have trouble swallowing, breathing, or speaking, go to the nearest emergency room right away. For the other signs, see a doctor promptly. You can also send photos through the consultation button on this page, but a message isn't a substitute for being examined in person.

When Should You Get a Second Calf Botox Session?

About 3 months after the injection, the treated nerve endings form new connections, and the muscle gradually gets its strength back. Injections that are too frequent can lead your body to make antibodies to the toxin, which can weaken later results, so the same area isn't retreated sooner than every 8 to 12 weeks.

Waiting longer than 3 months isn't a problem either. In the 6-month study above, calves were smaller at 6 months than at 3 months, so the 3-month mark isn't an automatic rebooking date. The second session is timed by whether the calf muscle starts to stand out again when you rise up on your toes.

Keep in mind that a second session isn't a fixed part of the plan. Some people decide the first result is enough for now, and others come back once the bulge returns. Everyone's legs are different.

How Much Does Calf Botox Cost per Session?

Calf Botox is priced by the number of units, not per leg. It isn't on the regular price list. It's listed on the clinic's Botox promotion page as body Botox for the calves or the trapezius (the muscle between the neck and shoulder).

Promotion period: September 1 to November 30, 2026, VAT excluded. Seoul clinic pricing, subject to change. The page doesn't say whether the units cover one leg or both, so confirm that at your consultation. How many units your legs need depends on the thickness of the muscle, which the doctor checks before setting the dose.

For international patients, there's a consultation fee of ₩10,000 with a counselor or ₩20,000 with the doctor, and it's waived if you have treatment the same day.

Calf Botox on a Korea Trip: Flying, One Visit, and Home

Unless you were sedated that day, there's no reason to push back your flight after calf Botox. The injection itself doesn't keep you grounded.

One visit won't transform your legs on the spot. The muscle relaxes over the first few days, and the outline shifts gradually toward a softer line after that, so the check at 6 to 8 weeks will most likely happen after you're back home. If you're thinking about a return trip for a second session, plan it around the 3-month mark rather than the first few weeks.

Once you're home, you can send photos through the clinic's consultation channel and ask about the timing of your next session. If you develop strong warning signs, such as trouble swallowing or breathing, see a local doctor or emergency room first instead of waiting for a reply.

The Bottom Line: Compare Photos at Week 0 and Weeks 6 to 8

Take a photo of your calves from behind before the injection, then again at 6 to 8 weeks, standing in the same spot under the same light. Those two photos show the change in your line far more clearly than a tape measure, and they're what makes the second-session decision easy.

When that time comes, the question to answer is simple: does the muscle bulge again when I rise onto my toes? Beautystone is a clinic in Seoul's Hapjeong area, and you can ask about your calves through the consultation button on this page. In your first message, include the date of your last calf Botox, the product and number of units, and anything that feels off when you walk.

Sources

• Calf circumference 8 weeks after 60 or 100 units per leg — Plast Reconstr Surg Glob Open, 2024

• Calf Botox dosed by muscle thickness, measured at 3 and 6 months — Aesthetic Plast Surg, 2019

• How calf fat thickness affects satisfaction after calf Botox — Plast Reconstr Surg, 2024

• Walking balance after Botox for enlarged calves — Gait Posture, 2026

• Early 6-month study of Botox for the inner calf muscle — Dermatol Surg, 2004

• When botulinum toxin starts working, how often it can be repeated, and who shouldn't have it — DermNet

• Xeomin prescribing information on units and spread of toxin effect — US FDA, 2023