Q. Is there any correlation between the time Botox takes effect and the time it takes to wear off? If Botox is still taking effect up to three weeks after injections does it mean it is most likely to take longer to wear off? Thank you
A. Good physiologic question. As others have mentioned:
- Botox onset is 5 to 7 days.
- Botox peaks at 10 to 14 days
- Botox duration averages 3 months
The physiology behind Botox and other neuromodulators such as Dysport and Xeomin is:
- Each molecule is the same but made differently by the different manufacturers. This will vary the onset, peak and duration of the prepared vial of medicine
- The molecule of botulinum toxin injected into the area of the presynaptic nerve end is broken down by enzymes in the interstitial space within an hour if the Botox does not attached to the nerve cell membrane receptor and stimulate synaptic absorption into the nerve ending. There are many reasons this can be prolonged or shortened depending on amount and strength of medicine and dilution, amount of enzyme available, concentration of cell membrane receptors, muscle activity and more.
- Once in the nerve end, a series of reactions occur for the Botox molecule to act in blocking the delivery of the neurotransmitter acetylcholine out of the nerve end, across the interstitial space without enzymatic breakdown, finding a muscle receptor and stimulation of muscle fibril contraction. Each step of the way is affected by many different factors in each patient.
- The more nerve ends “blocked” by Botox, the denser the inability for muscle contracture and the less movement of the injected muscle and therefore less wrinkling.
Other than the above noted averages, there is no answer as to whether late onset means late or early duration.
I hope this helps. All the best!