Botox typically produces visible changes within three to five days of injection, lasts three to four months, and treats both dynamic expression lines and — if started early enough — the formation of those lines in the first place. That dual action, plus the question of candidacy, sits at the center of new guidance from two facial surgeons interviewed by ELLE: double-board-certified facial plastic surgeon Dr. Jennifer Levine, MD, and Manoj T. Abraham, MD, F.A.C.S., founder of NYFACEmd.

How does Botox actually work?

Abraham describes the mechanism precisely. "Botox works by blocking a specific molecular neurotransmitter called acetylcholine. When Botox is administered very precisely by an expert injector to the tiny muscle fibers under your skin, these muscles relax and the lines and wrinkles smooth out," Abraham said. "This is not only useful to treat and smooth out these lines, but if you start early enough, before you have too many of these lines, it can prevent these lines from forming in the first place."

Levine distinguishes between dynamic lines, which appear with movement, and static lines, which remain when the face is at rest. Botox works particularly well on dynamic lines. Deeper static creases may need additional treatments.

From a preventive perspective, reducing the repeated folding of the skin may keep expression lines from becoming deeply established. "The goal is to preserve a pleasing balance of movement while softening the forces that contribute to creasing. That requires a detailed understanding of which muscles to relax and which movements to preserve," Levine said.

Who is a good candidate?

Botox is for adults noticing expression-related wrinkles who want to soften them, provided their medical history supports treatment, according to Levine. She assesses the whole face, not single lines. "Two people can have similar forehead lines but very different anatomy: one may be using their forehead muscle to help support a heavy brow, while the other is not. Their treatment plans should reflect that difference," Levine said.

Age ranges shift the treatment plan. Abraham's breakdown:

• 20s and 30s: Botox can treat early expression lines and prevent deeper ones. "The key is to do a gentle, precise treatment to relax the lines while maintaining natural expressions."
• 40s, 50s and older: Botox alone may not be sufficient for deeper lines; patients may need fillers, laser resurfacing, or a facelift or eyelid lift.
• After surgery: "I highly recommend keeping up with Botox treatments to maintain the results of the lift and keep areas smooth," Abraham said.

When should someone start?

Both experts agree the trigger is when expression lines begin to bother you — not a birthday. "A crease that starts to linger after your face relaxes can also be a useful signal," Levine said. "Muscle strength, skin quality, anatomy, and personal preferences matter more than a birthday."

Levine cautions that long-term evidence for prevention remains limited, so Botox cannot guarantee patients will never develop wrinkles. "Treatment should respond to a specific concern and an anatomical assessment, rather than an assumption that everyone needs to start early," she said.

What areas does Botox treat?

Abraham lists the common treatment zones:

• The "11" sign between furrowed brows
• Bunny lines along the top of the nose
• Horizontal forehead lines
• Crow's feet around the eyes
• Marionette creases at the corners of the mouth
• "Smoker's lines" around the mouth, even in nonsmokers
• "Peau d'orange" chin dimpling from mentalis muscle activity
• Neck bands from the platysma muscle

How fast does it work — and how long does it last?

Results appear within three to five days, but the full effect on forehead lines, frown lines and crow's feet may take up to 30 days, Levine said. Abraham has patients "exercise" the injected area by making the expression that causes their lines, which helps the muscles take up the medication faster.

Competitors act sooner: Dysport in two to three days, Daxxify in one to two days, according to Abraham, who adds that newer neuromodulators in development will have even quicker onset.

A first round of Botox lasts about three to four months. "The bad news is that pretty much everyone loves their Botox result, so the key here is consistency. If you come in for your next treatment before the Botox effect has worn off, the Botox will start to last a few weeks longer each time," Abraham said. The treated muscle fibers atrophy from lack of use — "It's like not going to the gym," he said.

Two caveats from Abraham:

• Treating more frequently than every three months risks the body becoming immune to the treatment, rendering it ineffective.
• Stopping altogether lets muscles regain activity and lines re-form. Stretching intervals to three to six months prolongs the effects over time.

Does lifestyle change candidacy?

Yes. "Sun exposure and smoking contribute to changes that Botox alone cannot address, making sun protection and good skin care essential parts of maintaining results," Levine said. Patients whose work relies heavily on facial expression may prefer subtle treatment; travel, events and comfort with maintenance also shape the plan.

Abraham cites evidence that frequent exercisers and metabolically active people break Botox down faster. These patients may need a higher dose and more frequent treatments.

Both surgeons close on the same principle: treatment should suit the person's anatomy and everyday life. "Preserving the warmth of a smile, the openness of the eyes, and the individuality of expression is central to a beautiful outcome," Levine said.