Botulinum toxin and dermal fillers
Botulinum toxin and dermal fillers are often mentioned together and sometimes given in the same appointment, but they work in different ways. Toxin relaxes muscles. Fillers add volume.
Botulinum toxin
Botulinum toxin is a purified protein that temporarily blocks the signal from a nerve to a muscle. Injected in small doses, it relaxes the targeted muscle. In aesthetic practice it is used for lines caused by movement, such as frown lines between the eyebrows, forehead lines and lines at the outer corners of the eyes. Clinics also use it to slim the jaw by relaxing the masseter muscle, and for excessive sweating.
The effect usually appears over several days and wears off gradually, commonly over three to four months, after which treatment can be repeated. Several brands are sold in Thailand, and they are not interchangeable unit for unit.
Common side effects include bruising, swelling or a headache. Less often, toxin spreads to a nearby muscle and causes a drooping eyelid or brow, or an uneven smile, which wears off as the toxin does.
Hyaluronic acid fillers
Most dermal fillers used today are made of hyaluronic acid, a substance found naturally in the skin, in gel form. They are injected to restore volume in the cheeks, lips, chin and temples, to soften folds such as the lines from nose to mouth, or to change the profile of the nose or jaw. How long they last depends on the product and the area, ranging from several months to over a year.
A useful property of hyaluronic acid fillers is that an enzyme, hyaluronidase, can dissolve them if the result is not wanted or a complication occurs. Other filler types, such as calcium hydroxylapatite or poly-L-lactic acid, work differently and cannot be dissolved in the same way.
Complications to know about
Most problems with fillers are minor: swelling, bruising, lumps or asymmetry. The serious risk is vascular occlusion, where filler enters or presses on a blood vessel and blocks blood flow. This can lead to skin damage and, rarely, loss of vision when the injection is near the nose, between the eyebrows or around the eyes. It is a medical emergency. Clinics should have hyaluronidase on hand and a plan for managing it.
Infection and delayed reactions can also occur. Tell the doctor about any history of cold sores, autoimmune conditions or previous fillers.
Questions to ask the clinic
- Who will do the injection, and can I check their licence with the Medical Council of Thailand?
- Which brand and product will you use, and is it registered with the Thai Food and Drug Administration?
- Is hyaluronidase kept at the clinic, and what happens if a complication occurs after hours?
- What is the total price, including any follow-up or touch-up visit?
Who should wait
People who are pregnant or breastfeeding, who have an active skin infection at the treatment site or who have certain neuromuscular conditions are usually advised not to have these treatments. A doctor should ask about your health and medicines before treating you.
Clinics in Thailand
Many Thai aesthetic clinics offer both toxin and filler treatments, often alongside thread lifts. Whichever clinic you consider, use the questions above, and check the licences described in choosing a clinic in Thailand.
Written by the SurgicalEyes editorial team. Last updated October 2026. See how we prepare and check guides in our medical review policy.