4 key side effects of botox injections
By Dr Tim Pearce, MBChB BSc (Hons) MRCGP
Botox works by inhibiting acetylcholine release in any synapse that releases it. The side effects are caused by inhibiting this normal nerve activity in areas that you would never intentionally treat, or by inhibiting too many synapses in areas that you might normally treat.
The first and most important thing we teach on our introductory course is the safety margins and injection techniques to minimise the risks of getting botox into important structures.
It is generally accepted that 1 cm from the orbital rim will keep the eye safe from unintended treatment. However, the published rate of eyelid ptosis is still a rather shocking 1% of treatments.
It is my experience that with detailed understanding of the anatomy, a precise injection technique and some practical techniques during administration (eg applying pressure within the orbit at the moment of injection) that this rate can be reduced to less than 1 in 10 000. All these are taught in the practical session of our courses.
4 most important side effects to avoid:
- Eyelid ptosis – a closed or partially close eyelid.
- Dry eyes/xerophthalmia – botulinum toxin has stopped the lacrimal gland working.
- Double vision- the lateral rectus muscle has been weakend by botulinum toxin spread.
- Brow ptosis- the frontalis muscle has been over treated, causing the forehead skin to slump.
If you have a patient who has had a ptosis it can be very upsetting (for both of you!).
The first thing is to examine the patient and review photographs to be sure it wasn’t a pre-existing asymmetry (it’s not uncommon for clients to spot old asymmetries or blemishes after a new treatment).
It’s also very common for people to google ‘botox side effects’ and self diagnose eyelid ptosis when actually it is a brow ptosis rather than the more severe eyelid problem.
The most important thing is to reassure that it will return to normal, starting from 6 weeks. The milder the drop the quicker it will recover. The next thing is to make sure that there are no associated symptoms like dry eyes or double vision.
Once the diagnosis is confirmed there is only one helpful treatment, which is the use of aproclonadine drops. These eye drops work on smooth muscle, not on the muscle under conscious control. The sympathomimetic effect means it acts like adrenalin does- to widen your eyes for a short period of time. At best it makes a helpful contribution, but it only lasts a few hours and repeated application is required. It is also of course unlicensed for this use, and has it’s own set of side effects to consider.
I would reserve the use of this for very emotionally affected or people with vision disturbance caused by the lid crossing the visual axis- a very rare outcome.
A Dry Eye
A dry eye is often a more bothersome side effect to live with, as it causes pain and even infection.
Regular use of eyedrops like Lacrilube will be required for 4 months. A close follow up if infection occurs and specialist should be informed if infection occurs as the eye does not have it’s primary defence.
It’s worth remembering that the entire industry based around the aesthetic use of botox was founded on the discovery that botox being used to treat the lateral rectus muscle in patients with strabismus also showed an improvement in the crows feet- from it’s very first use, we have known that botox spreads, and it can spread both ways!
Double vision caused by botox affecting the lateral rectus muscle is caused when product spreads while treating the orbicularis muscle.
The symptom only occurs when looking towards the affected side. There is little you can do to treat it other than reassuring that it will return to normal in 10 to 12 weeks or less, and that if severe they should not partake in activities that may put themselves or others at risk- for example driving. Review your safety margins, injection procedure and aftercare advice to prevent re-occurrence.
This is probably the most common side effect of the four. The heavy brow after botox is caused because apart from causing lines, the muscle is also involved in supporting the skin at rest. When it has been over treated the brows can drop.
The key is to not only consider that the frontalis muscle has been over treated, but also to consider whether or not the other muscle in the face (orbicularis oculi, procerus, and depressor supercilli) are in fact causing the brow ptosis through the imbalance caused by not treating them at the same time.
The change in the overall vectors affecting the eyebrows naturally will pull brows down if these muscles aren’t treated. As a result this means you can possibly solve or improve the problem in some people by treating these other muscles too.
Aside from that, learning should be taken about the dose and position of the injections in the frontalis so that in future less is given or the position is moved higher up the frontalis.