Classification of Dermal Fillers and Possible Side Effects
Dermal filler injections, one of the most commonly used applications in aesthetic dermatology, are preferred to reduce signs of aging, correct volume loss and provide skin rejuvenation. Today, more than 150 dermal filler products are used, and these fillers are classified according to their different content, duration of permanence and biological properties.

What are the Types of Dermal Fillers?
Fillers are basically divided into two main groups:

1. Biodegradable Fillers (Temporary or Semi-Permanent)
Hyaluronic Acid (HA): It is the most frequently preferred filler. Its effect can vary between 6-18 months. Its cross-link structure, particle size and concentration determine the duration of effect. It carries a risk of edema due to its hydrophilic structure.

Collagen: It has medium permanence and is rapidly absorbed by the body.

Calcium Hydroxyapatite (CaHA): It can be effective for up to 15 months by triggering collagen production.

Poly-L-lactic Acid (PLLA): It has a gradual effect and usually lasts up to 2 years after 3-4 sessions.

2. Non-Biodegradable Fillers (Permanent)
Polymethylmethacrylate (PMMA): Permanent, but carries the risk of foreign body reaction and granuloma.

Polyacrylamide Hydrogel: Highly permanent, but potential complications may last longer.

Side Effects and Complications of Dermal Fillers
Although filler injections are generally safe procedures, some side effects may occur. These are generally classified as early (within the first few days) or late (weeks-months later).

Early Side Effects
1. Injection Site Reactions
Pain, redness, tenderness, bruising (ecchymosis) and edema are the most common reactions.

To reduce the risk: small needles/blunt cannulas, slow injection, low volume, aspiration and cold compresses are recommended.

In case of bruising: topical arnica, vitamin K or light laser treatments may be preferred.

2. Infection
Usually bacterial (staphylococcus, streptococcus) or viral (herpes simplex) origin.

Prevention: sterile work, antiseptic cleaning and careful evaluation of the patient's medical history.

Treatment: Empiric antibiotics (e.g. amoxicillin-clavunate) and hyaluronidase injection if necessary.

3. Allergic/Hypersensitivity Reactions
Type I IgE-mediated reactions may be seen, although rare.

Symptoms: erythema, pruritus, edema, rarely anaphylaxis.

Treatment: antihistamines, short-term oral steroids if necessary.

Factors Affecting the Occurrence of Side Effects
1. Practitioner Factors
Anatomical knowledge, technical experience, avoidance of vascular areas and appropriate product selection reduce complications.

Risky areas: glabella, nose, alar base, temple.

2. Patient-Related Factors
Past cosmetic procedures, chronic diseases, medications used and allergy history should be carefully evaluated.

3. Product-Related Factors
Product purification level, cross-link structure and particle size affect the risk of complications.

Products with high quality standards obtained from reliable manufacturers should be preferred.

Strategies to Consider in Filler Applications (Summary)
Know the anatomy of the injection area well

Prefer blunt cannula in risky areas

Inject slowly, with low volume and low pressure

Apply aspiration before injection

Monitor the patient during the procedure

Provide hyaluronidase and antiviral/antibiotic support if necessary