Why is the frontalis muscle special?
The frontalis is a single broad muscle layer on the forehead. It extends from the hairline above to the brow bone below. It has one sole function: to raise the eyebrows. No other muscle in the face can lift the eyebrow; when the frontalis is suppressed, the eyebrow succumbs to gravity and drops. This is the anatomical reason for the complaint, "my forehead lines are gone, but my brows feel heavy."
The length and width of this muscle vary from person to person. In some patients, the frontalis extends to the upper edge of the forehead, while in others, the middle band is weak. This anatomical difference explains why each patient's forehead botox needs a different map. A standard "5 points, 4 units each" formula does not work.
Glabella-frontalis balance
It is often a mistake to inject botox into the forehead without treating the glabella (between the eyebrows). The glabella muscles (procerus, corrugator) pull the eyebrows down. The frontalis lifts them up. If the frontalis is silenced and the glabella is left active, the downward pulling force becomes greater than the upward lifting force, and the eyebrow drops. This is why forehead botox is almost always planned in combination with the glabella. The goal is to maintain the up-down balance, targeting only the upper frontalis fibers that produce horizontal lines.
In my clinic, I rarely fulfill a request for "forehead botox only." I explain this anatomy to the patient and suggest establishing balance with a small glabella support. If the patient does not want it, I reduce the dose further and proceed with a "mini forehead" model.
Incorrect forehead plan
- High dose in a single session
- Uniform injection across the entire forehead
- Needle near the brow arch
- Forehead only, without glabella
- Standard map without knowing the patient's face at all
Correct forehead plan
- Start with a low dose, evaluate after 2 weeks
- Personalized frontalis map
- At least 1.5 cm above the brow arch
- Planned in conjunction with glabella
- Decision after mimic + resting photos
Dose rationale and starting point
My preferred approach for forehead botox is the "start low, adjust" model. For female patients, a total frontalis dose of 6-10 units (Botox/Xeomin) is often sufficient. For men, due to larger muscle mass, 8-14 units are discussed. The doses are starting points, not "ideal"; an additional dose (touch-up) can be given at the control appointment on day 14.
I never give a very high dose in the first session. Because once botox is given, it cannot be undone. If the patient's brow drops, the only way to resolve it is to wait for the muscle to recover — and this waiting takes 2-3 months. Rather than making the patient experience this period, it is much safer to add 2-3 units in the second session.
Clinical note:A 1.5 cm safety margin at the brow arch is a clinical standard. If the needle is placed below this margin, the brow drops or a "Spock brow" (excessive elevation of the lateral ends) appears. I draw my boundary line on each patient's forehead, take a photo, and then place the needle accordingly.
What is felt, what is not felt afterwards?
The first 24 hours should look normal. Slight redness, pinpoint bleeding marks disappear within a few hours. From the 2nd-3rd day, when the eyebrow is lifted, a feeling of "not lifting completely" begins; this is a sign that it is working correctly. On day 14, the forehead should be completely smooth at rest, and lines should appear much fainter when making expressions.
If there are still prominent lines after day 14: an additional dose is considered. If the forehead feels very relaxed and the brow heavy: wait, it will ease as the muscle recovers. An artificial "lifted forehead" or "shining" sensation is usually an indication of an overdose; the dose is reduced in the next session.
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