ConditionSkin, hair & nails
Scar Formation
Scar formation is the body's natural way of repairing skin and tissue after injury, surgery, burns or acne. Collagen fibers fill the wound, but they are laid down less neatly than in normal skin, so a scar looks and feels different. Most scars fade and flatten over 12 to 18 months. Some become raised (hypertrophic scars or keloids), sunken (atrophic scars), or tight enough to limit movement (contractures). Good wound care, sun protection and early treatment with silicone, pressure or injections improve how scars look and feel.
Also called: Scarring, scar tissue formation, cicatrix, wound healing scars
At a glance
- What it is
- Fibrous tissue that replaces normal skin after a wound heals.
- Timeline
- Scars remodel and fade over 12 to 18 months or longer.
- Types
- Flat (fine line), hypertrophic, keloid, atrophic, contracture.
- Risk factors
- Infection, tension, deep or burn wounds, darker skin (keloids), genetics, smoking.
- Treatment
- Silicone gel or sheets, pressure garments, steroid injections, laser, surgery.
When to get help
See a doctor within a day or two
- A healing wound that becomes red, hot, swollen, painful or drains pus, or with fever
- A scar that suddenly bleeds, ulcerates or develops a non-healing sore
Book a routine appointment
- A scar that keeps growing beyond the original wound edges, itches or hurts
- A scar across a joint that limits movement
- A changing or new lump, color change or sore in an old scar, especially a burn scar
- Distress about the appearance of a scar
Usually safe to manage at home
- A new, pink, flat scar from a healed cut or surgical wound that is gradually fading
How scars form
Wound healing follows overlapping phases:
- Hemostasis (minutes): blood clots seal the wound.
- Inflammation (days 1 to 5): immune cells clean the wound of bacteria and debris.
- Proliferation (days 4 to 21): fibroblasts lay down new collagen and new blood vessels form; the wound fills with pink granulation tissue and the surface closes.
- Remodeling (3 weeks to 2 years): collagen is reorganized and strengthened; the scar flattens, softens and fades from red or purple to paler.
A scar never regains full normal skin strength (about 80% at best) and lacks hair follicles and sweat glands.
Types of scars
| Type | Appearance | Notes |
|---|---|---|
| Fine-line (mature) scar | Flat, pale line | The normal result of a clean, well-closed wound |
| Hypertrophic scar | Raised, red, firm, within the original wound | Appears within weeks; often improves over 1 to 2 years |
| Keloid | Raised, shiny, growing beyond the wound edges | Can follow minor injuries such as piercings or acne; rarely regresses; more common in darker skin |
| Atrophic scar | Sunken, pitted | Typical of acne scars and chickenpox |
| Contracture | Tight, pulls skin and joints | Common after burns; can limit movement |
| Stretch marks | Thin, lined streaks | A type of scar from rapid stretching |
What makes scars worse
- wound infection or delayed healing
- tension across the wound, such as over the chest, shoulders and joints
- deep wounds, burns and wounds left to heal slowly
- genetics and darker skin (for keloids)
- age: young people form more active scars
- smoking, poor nutrition, diabetes
- sun exposure during healing, causing darker scars
- picking at scabs
Reducing scarring as a wound heals
- clean the wound and keep it covered and moist with petroleum jelly and a dressing; moist wounds heal with less scarring than those left to dry and scab
- close wounds promptly when needed: lacerations should be repaired within hours
- avoid stretching the area during early healing
- protect from sun for at least 12 months with clothing or SPF 30 or higher sunscreen
- start silicone gel or sheets once the skin has closed, usually 2 weeks after surgery, for at least 2 to 3 months
- massage the scar gently once healed to soften it
- don't smoke
Treatments for established scars
- silicone gel or sheets: first-line for hypertrophic scars and keloid prevention
- pressure garments: for burn scars, worn most of the day for months
- corticosteroid injections: flatten and soften hypertrophic scars and keloids; may be combined with 5-fluorouracil
- laser treatment: pulsed dye laser reduces redness; fractional lasers improve texture and atrophic acne scars
- microneedling, chemical peels and fillers: for atrophic acne scars
- cryotherapy: for keloids
- scar revision surgery: to reorient or narrow a scar, or release contractures, often with grafts or flaps
- radiation therapy after keloid removal in selected cases, to reduce recurrence
- physical therapy and splinting for contractures
Over-the-counter creams such as onion extract and vitamin E have little evidence and vitamin E can cause skin reactions.
Frequently asked questions
How long does it take for a scar to form and fade?
The wound closes within 1 to 3 weeks, but the scar keeps remodeling for 12 to 18 months or longer. It usually starts red or pink and raised, then gradually flattens and fades to a paler color.
What is the difference between a keloid and a hypertrophic scar?
Both are raised scars from excess collagen. A hypertrophic scar stays within the original wound and often improves over time. A keloid grows beyond the wound edges, can follow minor injuries and rarely improves on its own.
How can I reduce scarring after surgery?
Keep the wound clean and moist, avoid stretching it, protect it from sun for at least a year, start silicone gel or sheets once the skin has closed, and gently massage the scar. Don't smoke, and follow your surgeon's wound care advice.
Can scars be removed completely?
No treatment can remove a scar completely, but many can make it much less noticeable. Options include silicone, steroid injections, laser, microneedling and scar revision surgery, depending on the type of scar.
Sources
This guide was written from current patient and clinical guidance, including:
- American Academy of Dermatology: Scars: diagnosis and treatment; Keloids
- International Advisory Panel on Scar Management: Updated international clinical recommendations on scar management
- MedlinePlus: Scars
- NHS: Scars
- American Society of Plastic Surgeons: Scar revision