Introduction

Aesthetic surgery, both invasive and non-invasive, is a common practice considered by people of all ages worldwide, who look for body sculpting, enhancement of physical appearance, and facial rejuvenation. Invasive cosmetic surgery is carried out by a plastic surgeon and offers more long-lasting effects.¹ Contrarily, non-invasive cosmetic procedures include practices that do not require incisions, or removal of skin tissue, but can also offer numerous benefits for various body image concerns, including wrinkles, discolouration, sagging skin, etc.² Additionally, non-invasive and minimally invasive procedures have fewer side effects, minimal post-operative complications, and quicker recovery.³

The technological advancements of the modern era have rendered non-invasive cosmetic surgery prevalent and accepted by more and more individuals, who seek to address certain body image concerns and boost their self-esteem and self-confidence.³ According to a survey conducted by the International Society of Aesthetic Plastic Surgery, 17.5 million non-surgical cosmetic procedures were performed globally in 2021.⁴ Injections, dermal fillers, laser treatments, light therapies, and chemical peels are some of the most popular techniques used in cosmetic dermatology.

Non-invasive procedures

Injectables

Botulinum toxin (i.e. Botox^®)

Botulinum toxins are neurotoxins obtained from different bacteria, most commonly Clostridium botulinum, and are known for their ability to reduce lines and wrinkles. Different formulations of these agents are injected into specific muscles and act by temporarily inhibiting the release of the neurotransmitter acetylcholine in motor neurons, thus preventing muscle movement for a limited time. One commonly treated area is the upper face for the lines between the eyebrows, forehead rhytides, crow’s feet, and brow lifting. Cosmetic applications in the lower face are also gaining popularity, with injections used for perioral lip lines, marionette lines, dimpled chin, jawline shape sculpting, and neck (platysmal) bands.⁵

Dermal fillers

The most common materials used as dermal fillers include hyaluronic acid (HA) and collagen. HA and HA-based fillers boost skin tone and elasticity thanks to their hydrating properties; by binding water, they aid in the direct volumisation of tissues, enhancing collagen production. On the other hand, collagen fillers act by restoring the collagen loss occurring with ageing, correcting volume loss and maintaining extracellular matrix health. Different types of collagen fillers have been produced, including those of bovine or porcine origin, human-derived, and most recent innovative products, such as hydrogels and recombinant human collagen. Overall, collagen fillers offer a variety of benefits for facial rejuvenation, however, certain types of fillers are associated with specific disadvantages like immunogenicity.⁶

Apart from the physical fillers mentioned above, biostimulatory fillers are also commonly injected to stimulate collagen and increase soft tissue volume. Agents such as polylactic acid, calcium hydroxyapatite, polycaprolactone, and polymethyl methacrylate are biomaterials that, upon injection, activate the body’s natural response to foreign materials and through a series of reactions, eventually, result in collagen deposition at specific sites. Referring to a person with cosmetic expertise is pivotal for optimising the performance of these fillers, and analysing their safety profiles.⁶

Laser treatments

Laser therapy is vastly used nowadays, from common hair removal practices to targeting specific tissues to cope with different skin problems. Lasers of different wavelengths act by getting absorbed in varying skin depths by endogenous chromophores like water, melanin, and haemoglobin. The selection between the types of resurfacing lasers, ablative, non-ablative, or fractional, should be made by an experienced operator who will discuss with the patients all the potential risks, costs, sessions, and recovery times needed.⁷

Various types of lasers have been developed with distinct indications:⁷

• Ruby: effective in colourful tattoo removal
• Alexandrite: also effective in tattoo removal
• Intense pulsed light therapy: is indicated for acne, rosacea, and vascular lesions
• Nd:YAG: used for hair removal, haemangiomas, and deep, pigmented lesions
• Diode: indicated for hair removal, and darker tattoos
• Er:YAG: has effective skin-lightening properties and is commonly used for discolouration and sun-damaged skin
• CO₂: can resurface the skin, reduce wrinkles, and treat scars⁷ 

Skin tightening and lifting

Ultrasound therapy 

High-intensity focused ultrasound (HIFU) and micro-focused ultrasound (MFU) are methods that focus ultrasound energy on the body and destroy small tissue volumes through heat. Specifically, HIFU accumulates high-frequency ultrasound beans at specific tissues and causes molecular vibrations and microthermal damage to the area without affecting the epidermis or adjacent sites. This technique results in collagen remodelling and fat ablation, offering effective facial lifting and wrinkle reduction.⁸ Similarly, the MFU technique uses more precisely focused energy to target subcutaneous tissue and cause thermal coagulation points to the area without affecting other layers of the skin. The accumulated heat in the area causes collagen fibre denaturation, encouraging new collagen production. A commercial device, which uses MFU with visualisation of the exact skin depths where the energy can be applied, is one of the most popular techniques used for facial, neck, and décolletage lifting and tightening, and is known as Ultherapy^®.⁹

Radiofrequency

The aesthetic application of radiofrequency energy (RF) has been increasingly employed over the past 15 years. RF uses electromagnetic currents to generate heat in specific tissues like underlying skin and soft tissue, muscles, and fat. This energy results in the contraction of collagen by immediately cleaving collagen fibres and triggering wound-healing processes for de novo collagen production and elastin reorganisation. Appropriate temperature control and advanced RF technologies, like hybrid systems with monopolar and bipolar RF, and fractional RF offer safe and effective advantages in improving skin’s firmness and elasticity, reducing cellulite, and managing fat reduction.¹⁰ 

Non-surgical fat reduction

Numerous non-invasive and minor invasive methods have been produced to reduce adipocytes (fat cells). Ultrasonic lipolysis and radiofrequency lipolysis are modern methods commonly used for fat reduction,¹¹ while further techniques include:

Cryolipolysis

Cryolipolysis, also known as fat freezing, is a well-known alternative to liposuction, acting as an effective body contour method. This procedure uses specific devices, which cool the skin and underlying fat cells and trigger their death while keeping the skin and other cells intact. Eventually, dead fat cells are eliminated by the body, resulting in fat reduction, with the results being visible from a few weeks up to several months after the procedure. An average fat reduction of 10%-25% can be obtained per treatment, therefore multiple sessions may enhance the outcomes. Cryolipolysis is generally indicated for minor to moderate fat reduction and although is considered typically safe, certain complications have been observed, underscoring the importance of referring to a qualified professional for treatment¹²

Injection lipolysis

Injection lipolysis uses active substances such as sodium deoxycholate (e.g. Kybella^®), which have fat-dissolving properties and act by destroying adipocytes¹¹

High-intensity focused electromagnetic (HIFEM) technology

HIFEM technology uses a device which produces electrical currents via an electromagnetic field, able to contract muscles. This muscle movement requires energy, which is obtained from adipocytes and thus results in body fat reduction and muscle repair¹¹

Other procedures

Chemical peels

Chemical peels refer to a skin resurfacing technique where chemical solutions are applied to exfoliate and remove layers of the skin, offering new skin growth and improved appearance. Specifically, diverse acids, including α-hydroxy acids (e.g. glycolic acid), β-hydroxy acid (e.g. salicylic acid), trichloroacetic acid, tretinoins, phenols, and combined solutions can induce changes in the dermis and/or epidermis, depending on their strength. Acids can act as superficial, medium, or deep surface peels and can target acne, pigmentation, photoaging, and scars. In-office visits may be necessary to decide on the appropriate type of peel for each patient’s needs and discuss potential side effects and contraindications.⁷

Microdermabrasion

Microdermabrasion is a cosmetic procedure that uses a specific instrument with crystals, such as aluminum oxide and sodium chloride that cause a mechanical abrasion on the skin, removing its superficial layers. The instrument also consists of a vacuum, which collects the crystals and skin debris, revealing an improved skin texture by stimulating collagen and fibre production. It is a low-risk method predominately effective for photoaging, acne scars, and stretch marks, offering a gradual amelioration through multiple sessions.⁷

Microneedling

Microneedling utilises different devices, such as Dermaroller^®, Dermapen^®, Derma Stamp^®, AquaGold^®, and microneedle patches that can be applied for scar removal, moisturising, hair loss, rejuvenation, melasma, and vitiligo. Microneedling is a painless, possibly self-administrable technique, which is effective alone or in combination with topical formulations like peels or platelet-rich plasma, aiding in their absorption.¹³

Mesotherapy

Mesotherapy uses microinjections of substances including HA, vitamins, minerals, amino acids, and other antioxidants that improve skin appearance by increasing fibroblast and collagen synthesis. This kind of therapy is considered safe and can target different preventative and therapeutic needs based on the patient's age and the severity of the problem, though the results are not permanent.¹⁴

Carboxytherapy

Carboxytherapy involves microinjecting carbon dioxide into affected areas with different therapeutic aims. It results in intradermal collagen reorganisation and vasodilation and can help in skin ageing, alopecia, cellulite, localised fat deposits, stretch marks, dark circles, scars, psoriasis, and vitiligo.¹⁵

Summary

Non-invasive aesthetic surgery is widely practised globally offering body sculpting and skin rejuvenation outcomes. Avoiding the scalpel is an increasing demand, which has led to some astonishing technological advancements that aim to augment individuals’ appearance and self-esteem by targeting concerns such as wrinkles, discolouration, sagging skin, and fat. Botulinum toxin injections, dermal fillers, laser treatments, ultrasound therapy, RF, cryolipolysis, chemical peels, microneedling, and microdermabrasion are some of the most innovative techniques utilised for their cosmetic benefits.

While non-invasive or minimally invasive cosmetic treatments are associated with fewer side effects and less recovery time, extreme caution is always advised. Individuals looking for such solutions must have realistic expectations and understand that results may be modest and transitory, necessitating multiple sessions with a high cost. Furthermore, not all people are suitable for all techniques. Proper patient selection and analysis of the skin’s anatomy and properties must be made by an experienced professional. Highlighting the potential side effects, contraindications, and post-treatment care associated with each technique are also factors that should be discussed in-depth with an expert