Aesthetic Treatment Glossary
Plain definitions of the terms you will meet when reading about aesthetic treatments.
In Brief
This glossary gives plain definitions of the terms used in aesthetic medicine, from HIFU and SMAS to subcision and hyaluronidase.
Ablative laser
A laser that removes thin columns or layers of skin, such as CO2 or erbium. Recovery is longer than with non-ablative lasers. Read more
Acne scar
A permanent change in skin texture after inflamed acne. Most are depressed (atrophic), and the main types are rolling, boxcar and ice-pick. Read more
Alexandrite laser
A 755 nm laser used for hair removal and some pigment treatments, mostly on lighter skin tones. Read more
Androgenetic alopecia
Pattern hair loss, driven by genetics and hormones. It is the most common cause of hair thinning in men and women. Read more
Atrophic scar
A scar that sits below the skin surface because tissue was lost during healing. Read more
Biostimulator
An injectable that aims to prompt the body to make new collagen, such as calcium hydroxylapatite or poly-L-lactic acid. Read more
Botulinum toxin
A purified neurotoxin injected in small doses to relax selected muscles, used for movement lines and enlarged jaw muscles. Read more
Boxcar scar
A wide acne scar with a flat base and defined vertical walls. Read more
Calcium hydroxylapatite
A biostimulatory filler material made of microspheres in a gel carrier. Read more
CO2 laser
An ablative laser at 10,600 nm, often delivered in fractional columns for texture, scars and resurfacing. Read more
Collagen
The main structural protein in skin, which falls with age and sun exposure. Read more
Cryolipolysis
Controlled cooling used to reduce localised fat. A rare side effect is paradoxical adipose hyperplasia. Read more
Dermal filler
An injectable gel used to restore volume or refine contour. Most are hyaluronic acid. Read more
Fitzpatrick scale
A six-point scale of skin type based on how skin responds to the sun. It guides laser settings. Read more
Fractional laser
A laser that treats tiny columns of skin and leaves the surrounding skin intact, which helps healing. Read more
HIFU
High-intensity focused ultrasound, which heats tissue at set depths under the skin without incisions. Read more
Hyaluronic acid
A sugar molecule that holds water. In gel form it is used in most dermal fillers and skin boosters. Read more
Hyaluronidase
An enzyme injected to break down hyaluronic acid filler. It is used for overfilled areas and in emergencies. Read more
Ice-pick scar
A narrow, deep acne scar that runs like a tract through the dermis. Read more
Keloid
A raised scar that grows beyond the original wound. It is managed differently from pitted scars. Read more
Masseter hypertrophy
Enlargement of the chewing muscle at the jaw angle, which can make the lower face look square. Read more
Melasma
Chronic brown-grey patches, usually on the cheeks and forehead, influenced by sun and hormones. It can return after treatment. Read more
Monopolar radiofrequency
Radiofrequency energy delivered from one electrode with a return pad, used to heat deeper tissue. Read more
Nd:YAG laser
A laser at 1064 nm that penetrates more deeply, used for hair removal, vessels and pigment, including on darker skin. Read more
Non-ablative laser
A laser that heats skin without removing the surface, so recovery is usually shorter. Read more
PDRN
Polydeoxyribonucleotide, a DNA-derived ingredient used in some skin boosters. Read more
Picosecond laser
A laser with pulses in trillionths of a second, used for pigment and tattoo ink. Read more
Pillow face
An overfilled appearance caused by too much filler or filler migration. Read more
Post-inflammatory hyperpigmentation
Dark marks left after inflammation, such as acne or a burn. It is more common in Asian and darker skin. Read more
Radiofrequency
Electrical energy that heats tissue. It is used for skin tightening and body contouring. Read more
Rolling scar
An acne scar with a wavy surface, caused by fibrous bands pulling the skin down. Read more
Rosacea
A long-term condition with facial redness, visible vessels and sometimes bumps. Read more
Skin booster
An injectable placed superficially to improve hydration and skin quality rather than shape. Read more
SMAS
The superficial musculoaponeurotic system, a fibrous layer of the face that surgeons lift in a facelift. Read more
Subcision
A needle technique that releases the fibrous bands under tethered scars. Read more
TCA CROSS
Focal application of concentrated trichloroacetic acid into ice-pick scars. Read more
Telangiectasia
Small, visible dilated blood vessels on the skin. Read more
Thread lift
A procedure that places absorbable sutures under the skin to reposition mild to moderate sagging. Read more
Tyndall effect
A bluish tint seen when filler is placed too superficially, often under the eyes. Read more
Vascular occlusion
A blocked blood vessel caused by filler. It is an emergency that can harm skin or vision. Read more
General information only. Last updated 3 November 2026.