If onabotulinumtoxinA, a neurotoxin derived from a type of bacteria called Clostridium botulinum, is a term you’ve never heard before, you’re not alone.

Otherwise known as Botox Cosmetic, this prescription medication is used to temporarily paralyze facial muscles and help make moderate to severe forehead lines, crow’s feet, and frown lines less noticeable.

Considered a relatively safe and straightforward procedure, according to a 2016 study, you can typically expect to see and feel the full effects of Botox 10 to 14 days after the procedure.

We talked with a few experts to find out how long it takes for Botox to work and how long you can expect to see and feel results.

In general, you can see the effects of Botox as early as 3 to 4 days after an injection. Dr. Oscar Trujillo, a facial plastic surgeon at Columbia University Irving Medical Center, says most patients will see results within 10 to 14 days but should wait the full 14 days to see the maximum results.

While the results vary based on factors such as the area treated and frequency of injection, Trujillo says results generally last 3 months.

In addition to the area treated and frequency of injection, the timeline of efficacy is also affected by the dose of Botox. According to Dr. Melanie Palm, a board-certified dermatologist and cosmetic surgeon, it appears that the higher the dose given in an area, the longer the effect on the muscles.

“Therefore, lighter dosing that looks most ‘natural’ may last only 6 to 8 weeks, while heavier dosing (more units) could last more than 6 months but ‘paralyze’ the appearance of muscles, such as the frown lines,” she said.

Because of the difference in results, Palm says this delicate balance between dose, desired look, and duration is something you should discuss with your healthcare provider prior to treatment to set proper expectations.

The most common areas of the face for Botox include the forehead, around the eyes (crow’s feet), and between the eyebrows. In general, Trujillo says the finer the lines, the faster the results.

“For example, patients will generally see results more quickly in areas such as the corners of the eyes (crow’s feet) and fine forehead lines,” he said.

However, Trujillo says the results may take longer for areas where the lines are deep or etched. “This includes the lines between the eyebrows or very deep or etched forehead lines,” he said.

Moreover, Palm says it’s not that Botox injected in different areas takes different amounts of time to see results — it’s really the concentration of product injected and how it’s injected into the muscle that determines the ultimate effect.

That said, “It is possible that larger muscles receiving less units (think forehead) may appear to kick in slower than a smaller muscle (a weaker frown) receiving more units,” she explained.

While some results are noticeable after 3 or 4 days, it can take a few weeks to see maximum results. Why this delay?

Botox binds at a connection point between muscles and nerves called the motor endplate. When this happens, Palm says the nerves “bark orders” at the muscle to move, and the motor endplate of the nerves, which is the megaphone, hollers at the nerve to contract.

“Botox binds to a specific protein called SNARE at the motor endplate that sends chemical messages (the shouting protein, aka, acetylcholine) to tell the muscle to move,” said Palm.

Botox silences this game of telephone, and without the chemical acetylcholine being released, Palm says the muscle doesn’t move.

Although Botox binds quickly, Palm says the shutting off of SNARE, and the silencing of acetylcholine takes several days. This explains why the onset of Botox isn’t immediate, but rather takes several days.

“Botox is administered by injection under the skin, where it is absorbed by nerve cells in contact with the muscle,” said Trujillo. In very basic terms, Trujillo says it takes time for Botox to take effect on the muscle and stop or weaken the muscle contraction that causes the lines and wrinkles to appear on the surface of the skin.

“Once those muscles stop contracting, the lines or wrinkles release, resulting in an improved appearance of the skin,” he added.

It’s working when your lines start to fade away. “The treated area will appear smoother and look more refreshed,” said Dr. Sapna Palep, founder of Spring Street Dermatology.

After your first treatment, Palep says you may feel a slightly tight sensation or a feeling of heaviness, which will subside in 1 to 2 weeks. You can typically tell that Botox is starting to wear off when you can see dynamic lines again with movement.

When it comes to finding a provider to administer Botox, the first criteria is to go with a board-certified physician. Commonly, people will seek treatment from a board-certified dermatologist or plastic surgeon.

To find a board-certified dermatologist, you can search using the American Academy of Dermatology’s Find a Dermatologist tool. If you’re looking for a board-certified plastic surgeon, you can use the American Society of Plastic Surgeons’ Find a Plastic Surgeon Near Me tool.

When in doubt, talk with your healthcare provider about referrals in your area.

Making the decision to get Botox injections isn’t something you should take lightly. While the procedure is simple and generally considered safe, it’s still an elective procedure that comes with risks.

Knowing the risks ahead of time, as well as the proper dose and timeline to meet your needs, can help you make an informed decision.