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Cortisone Injection vs Photodynamic Therapy

Cortisone Injection: A tiny shot of diluted steroid into one inflamed acne cyst. It flattens that spot in a few days. It treats the bump, not the acne.

Photodynamic Therapy: A light-activated drug applied in the office, then switched on with a lamp or laser. It is the strongest non-drug option for inflammatory acne, and the downtime is a real week.

Reviewed by Dr. Schwarz, Board-Certified Dermatologist
Last updated: 10/22/2026
Editorial illustration for Cortisone Injection, based on the entry’s treatment or equipment reference.Editorial illustration for Photodynamic Therapy, based on the entry’s treatment or equipment reference.
Choose ifKey differencesWhat is it?What it treatsTreatment areasSkin tonesHow it worksBefore your treatmentDay of treatmentAfter your treatmentRisksCostQuestionsRelated

Choose Cortisone Injection if…

Choose for one painful acne cyst that needs to flatten fast, or for keloids and patchy hair loss.

  • A single painful cyst before an event
  • A raised keloid
  • A patch of alopecia areata

Choose Photodynamic Therapy if…

Choose to treat a whole area of sun damage at once — or as a strong non-drug option for stubborn acne — with a real week of downtime.

  • Many precancerous patches on the face or scalp
  • You can stay out of light for 48 hours
  • You can take a week of redness
Fine together

Can you have both?

A cortisone injection can calm a single painful cyst during a photodynamic therapy plan for acne.

Key differences

● Cortisone Injection
● Photodynamic Therapy
DowntimeNone → 2+ weeks
None
3–7 days
PainMinimal → Needs anesthesia or sedation
Mild
Moderate
Results showImmediately → 3+ months
Within days
1–4 weeks
How long it lastsWeeks → Years or permanent
Weeks
1–2 years
Visits neededOne → Every few months
Every few months
A short series (2–3)
Cost per visit$ → $$$$$
$
$$
ReversibleYes, can be undone → No, permanent
No, permanent
No, permanent

What is it?

Cortisone Injection

Photodynamic Therapy

What is it?

It is injected into a lesion.

An intralesional steroid calms local inflammation or scarring.

It differs from joint injections.

It is not a systemic steroid treatment.

The diagnosis matters.

Infected or uncertain lesions should not be injected.

Side effects can last.

Skin thinning, fat loss and pigment change may persist.

It pairs medicine with light.

A photosensitizing medicine is activated by a set light exposure.

It treats precancers.

It is used for actinic keratoses and some superficial lesions.

It differs from LED therapy.

It is not ordinary LED or UV treatment.

Light avoidance is needed after.

Sunscreen alone may not prevent activation.

What it treats

Evidence level
Cortisone Injection
Photodynamic Therapy
Strong evidenceMost established uses
Inflamed acne on light skin. The spots sit in a patch of pink, and the ring of redness around each one is easy to see. A few have a yellow-white head, and the skin between them is dry and flaking.

Acne

Flattens a painful cyst within days.

A raised, smooth, firm scar on the upper chest on light skin. It is shiny pink-red and hairless, and its edges spread well past the small mark it grew from.

Keloids

Softens and flattens raised scars.

A round smooth bald patch on the scalp.

Alopecia Areata

Regrows hair in patches.

Existing educational image of Actinic Keratosis

Actinic Keratosis

Clears 75–90% of spots.

Moderate evidenceSome supportive research
A smooth, dome-shaped lump about two centimetres across on the upper back on pale skin, with a tiny dark pore at its center and faintly pink skin over it.

Epidermal Inclusion Cyst

Calms an inflamed cyst.

Existing educational image of Basal Cell Carcinoma

Basal Cell Carcinoma

Treats superficial types.

Limited evidenceEarly or small studies
—
Inflamed acne on light skin. The spots sit in a patch of pink, and the ring of redness around each one is easy to see. A few have a yellow-white head, and the skin between them is dry and flaking.

Acne

Used for stubborn acne.

Not effective
dark keratin plugs in dilated pores on the nose and adjacent left cheek, with the face turned to the person’s right on light skin.

Blackheads

Not for clogged pores.

AI-generated educational illustration of Melanoma: 1. Melanoma Header — Light Skin; Lighter skin. Not a clinical photograph.

Melanoma

Needs excision.

Can make it worse
Acne scarring on light skin. Small sharply cut pits and broad shallow dips across a cheek, several sitting inside faint flat pink marks, with no active spots.

Acne Scarring

Can cause dents in skin.

Flat tan patches with soft irregular edges across the forehead and upper cheek of an adult with light skin, the surface completely smooth.

Melasma

Light can darken patches.

Treatment areas

Treatment areas

The specific lesion, scar or affected patch determines the treatment site; there is no fixed body distribution.

Face; the selected area depends on the concern and treatment plan.

Skin tones

Skin tone
● Cortisone Injection
● Photodynamic Therapy
Lighter skin
Low risk
A small dent is possible.
Low risk
Redness and peeling.
Medium skin
Some risk
Lighter patches can show.
Some risk
Temporary darkening possible.
Deeper skin
Some risk
Lightening and dents are more visible; low doses help.
Some risk
Dark marks are more likely; strict light avoidance helps.

How it works

Cortisone Injection

Photodynamic Therapy

How it works
Cortisone Injection mechanism diagram. Medicine is placed in a lesion: A clinician injects an appropriate corticosteroid preparation. Inflammatory signaling decreases: The steroid reduces local immune and inflammatory activity. The lesion may soften or flatten: Response depends on the condition, dose, and placement.
Photodynamic Therapy mechanism diagram. A photosensitizer is applied: The selected medicine accumulates in the prepared treatment area. Light activates the medicine: A matched light regimen produces reactive molecules. Selected cells are damaged: Inflammation and healing follow; treatment response varies.
Diagram explanation

Medicine is placed in a lesion: A clinician injects an appropriate corticosteroid preparation. Inflammatory signaling decreases: The steroid reduces local immune and inflammatory activity. The lesion may soften or flatten: Response depends on the condition, dose, and placement.

Schematic illustration. Technique and response vary. This explains a mechanism and does not specify treatment settings.

A photosensitizer is applied: The selected medicine accumulates in the prepared treatment area. Light activates the medicine: A matched light regimen produces reactive molecules. Selected cells are damaged: Inflammation and healing follow; treatment response varies.

Schematic illustration. Technique and response vary. This explains a mechanism and does not specify treatment settings.

Before your treatment

Cortisone Injection
Photodynamic Therapy
2–4 weeks before
Not specified

2 weeks before: Sun and tanning: Avoid sun and tanning for 2 weeks.

Before you book: Time off: Clear several days, especially the 48 hours after, when you must stay out of sunlight and bright indoor light.

The week before

Do not pick: Do not pick, squeeze or heat the spot.

5 to 7 days before: Actives: Stop retinoids and exfoliating acids.

Day of treatment

Cortisone Injection
Photodynamic Therapy
Before you arrive

Clean skin: Wash your face and skip makeup on the area.

Not specified
Arrival & prep

The provider checks that the spot is an inflamed acne cyst and not a boil.

Photos, consent covering the off-label use and the downtime, and a medication review.

Treatment

The skin is wiped with alcohol.

A very fine needle goes just into the bump and a small amount of fluid goes in, under 10 seconds per spot. The sting is sharp for a few seconds, worse if the cyst is already tender, but most people rate it lower than they expect. Numbing does not help much — the needle stick is the whole procedure.

Skin is cleaned and degreased, sometimes with microdermabrasion or an acetone wipe, so the drug soaks in evenly.

The solution goes on and you wait 20 minutes to 3 hours in a dim room. Then eye shields go on and you sit under a blue or red light for 8 to 20 minutes, or a laser or IPL is passed over. Stinging builds and peaks at the end; cold air helps.

Before you leave

A tiny red dot, sometimes a small raised bleb that flattens within an hour.

The least comfortable procedure on this list.

After your treatment

Cortisone Injection
Photodynamic Therapy
First 24 hours

Days 1 to 2: The bump softens and the ache fades.

First 48 hours: Stay strictly out of sunlight and bright indoor light; daylight through a window can trigger a severe reaction.

Days 2–7

First few days: A pinprick mark, sometimes a small bruise, fading over a few days.

Days 3 to 7: Most cysts are flat.

Days 4 to 10: Peeling and flaking, sometimes in sheets.

Weeks 2–4
Not specified

Weeks 1 to 2: An acne flare is common in the first week or two, before improvement starts.

Time to results

24–48 hours for a cyst

2–4 weeks

How long results last

Treats only that spot

Treated spots clear; new ones may form

Risks

Risks
  • Dent in the skin
  • Lighter patch of skin
  • Visible small vessels
  • Dark patches
  • Prolonged redness
  • A cold sore outbreak

Cost

Per session

Roughly $50 to $250 per office visit in the US, usually billed as an office visit plus a procedure charge rather than per spot.

In the US, PDT for acne generally costs about $400 to $1,500 per session, so a course commonly lands between $800 and $4,000.

Insurance

Insurance often covers it, since acne cysts count as medical rather than cosmetic.

Insurance does not cover PDT for acne, because the approved indication is precancerous sun damage.

Questions

Cortisone Injection

Photodynamic Therapy

Individual Questions
How fast does a cortisone shot work on a cyst?

Softening begins within 24 to 48 hours and most spots are flat by day three to five. That figure traces back to one small 1983 trial — it matches what dermatologists see but has never been tested at scale. The mark left behind takes weeks longer, and the injection does not speed that up.

Will it leave a dent?

It can. A shallow depression happens when the dose is too strong, so a lower concentration is the main protection. It is uncommon — most dermatologists see it in well under one patient in a hundred — and it often fills in over several months. But it is not reliably temporary. About half the clinicians who do see it report it lasting more than six months, and occasionally it is permanent. That is why you ask what concentration is being used.

Can I get one before an event?

Yes, the most common reason people ask. Aim for three to five days ahead so the swelling has time to drop. A same-day injection rarely looks better by that evening.

Does it stop acne from coming back?

No. It treats only the spot it is injected into. Preventing the next cyst needs a daily treatment plan, and the guidelines call this an add-on.

Is it safe on deeper skin tones?

Yes. The risk is a lighter patch at the site, more noticeable and slower to fade on deeper skin tones. A lower concentration reduces it, so ask.

Is this approved for acne?

Not in the United States, strictly speaking. The FDA labeling lists intralesional use for keloids, alopecia areata, discoid lupus and others. Acne is not on it. Off-label use for an acne cyst is routine, legal and recommended by the American Academy of Dermatology, but almost nobody says it out loud. In the UK, NICE withdrew its recommendation in 2026 after UK-licensed triamcinolone injections stopped being available — a supply and licensing decision, not a safety one.

Is photodynamic therapy approved for acne?

Not in the US. It is FDA-approved for precancerous sun spots; using it for acne is off-label. That is legal and common, but it means no standard protocol and results that vary between clinics.

How bad is the downtime really?

Plan for 5 to 7 days of a visibly red, then swollen, then peeling face, with the worst in the first 48 hours. It is closer to a medium-depth peel than a laser facial.

Why do I have to stay out of the sun for 48 hours?

The drug is still in your skin, and sunlight — including through a car or office window — activates it and can cause a severe burn. This is the most important instruction of the treatment.

Does it cure acne?

No. Improvement typically lasts 6 to 12 months and repeat courses are often needed. It does not treat scars or existing brown marks.

Is it safe on deeper skin tones?

It can be done, but the risk of lasting dark patches is meaningfully higher, because the treatment works by causing strong inflammation. A shorter incubation, a lower light dose and an experienced provider make a large difference.

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