Topical & Intralesional Therapy for Nail Psoriasis (JAAD 2026)

30-second key takeaways

Key Points

Source: a June 2026 JAAD Letter from the Editor by Dr. Dirk Elston, commenting on Mello et al.'s pharmacokinetic study of periungual methotrexate (MTX) injection and reviewing topical-to-intralesional nail psoriasis therapy. Expert opinion + small studies, not a large RCT.
Why it's hard: creams barely penetrate the thick nail plate, and the matrix (where the nail grows from) lies deep in the skin. Nail psoriasis with psoriatic arthritis usually needs systemic therapy; but for those without arthritis who don't want systemic drugs, it is especially stubborn.
Topical: vitamin D analog ointments (calcipotriol, ± a steroid combination) are the Taiwan-NHI-covered topical base for psoriasis; topical MTX 1% gel shows partial efficacy, and fractional CO2 laser-assisted delivery improves some parameters (Moftah 2024 RCT); 20% urea + calcipotriol outperformed some intralesional injections in one comparison.
Intralesional (advanced option for refractory disease): for topical-refractory patients, 25 mg/mL intralesional MTX worked well (Chaiyabutr 2022 literature review); low-dose MTX injection may also work (Seidel 2025, 4 cases). Digital / palmar / wrist nerve blocks make matrix injection painless.
Mixed evidence: whether MTX or corticosteroid injection is better is inconsistent — some data favor depot corticosteroid over intralesional MTX (Kassem 2024), others favor more sustained effect with MTX (Starace 2022 pilot). There is no single clear "best" injectable yet.
New pharmacokinetic finding (Mello et al.): a single periungual MTX injection induced multi-month remission; plasma MTX compared favorably to oral/parenteral with relatively low clearance, suggesting a slow-release matrix depot that may explain the sustained effect. The authors call this an important safety step but note more study is needed to confirm the depot's safety equals weekly oral/parenteral dosing.
Taiwan reality: topical vitamin D analogs / retinoids — calcipotriol monotherapy, the steroid combinations (e.g. Daivobet, Enstilar), tazarotene, calcitriol — are NHI-covered (for plaque psoriasis, with weekly dose caps). But intralesional injection (MTX/steroid/5-FU), CO2 laser-assisted delivery, and topical MTX gel have no nail-psoriasis indication under Taiwan NHI — they are out-of-pocket and off-label.

What is nail psoriasis? How to tell it from a fungal nail?

Nail psoriasis is psoriasis affecting the nails. About half of psoriasis patients develop nail changes during the disease course; the rate is higher with psoriatic arthritis. It can occur alone, and may show up in the nails before obvious skin lesions — so it is often mistaken for a fungal nail (onychomycosis).

Nail psoriasis features differ depending on whether the matrix or the nail bed is involved. Common signs:

Figure 1. Six common signs of nail psoriasis. Pitting and crumbling arise from matrix involvement; oil-drop discoloration, onycholysis, subungual hyperkeratosis, and splinter haemorrhage from nail-bed involvement. This matters for treatment — matrix lesions (pitting, deformity) are injected at the matrix, nail-bed lesions (onycholysis, hyperkeratosis) at the nail bed.

Difference from a fungal nail (onychomycosis): a fungal nail usually starts in one nail, spreads distal-to-proximal, has fungus, and often comes with athlete's foot; nail psoriasis is often symmetric across nails, with pitting and oil-drop discoloration, and patients often have scalp/elbow/knee psoriasis. But the two overlap and can coexist — so if uncertain, clinicians do KOH microscopy/culture and sometimes a biopsy, to avoid treating psoriasis with antifungals indefinitely without effect. See our separate article on toenail-deformity differential diagnosis.

Why is nail psoriasis especially hard to treat?

Three structural reasons:

Poor drug penetration: the nail plate is thick and dense, so ordinary creams applied on the nail surface barely get through to the diseased matrix or nail bed. That is why "topicals often don't work for nail psoriasis."
The lesion sits deep: the matrix (where the nail grows from) is at the nail root, covered by skin; getting the drug there requires either laser/penetration enhancement to breach the nail barrier, or direct injection.
Slow growth, slow feedback: nails grow slowly (fingernails ~3 mm/month, toenails slower), so any treatment takes several months before healthy new nail shows — judging efficacy requires patience.

For these reasons, nail psoriasis treatment is often tiered: mild cases or those wanting a gentle start begin with topicals; only when topicals fail, or the lesion is in the hard-to-reach matrix, are advanced options like intralesional injection or laser-assisted delivery considered.

Important: nail psoriasis is a warning sign for psoriatic arthritis

Don't focus only on the nail — watch the joints:Nail psoriasis is closely linked to psoriatic arthritis; psoriasis patients with nail involvement have a higher risk of later arthritis (especially distal interphalangeal joints). Elston opens the editorial by noting nail psoriasis "is often associated with psoriatic arthritis requiring systemic treatment." So if you have nail psoriasis plus morning joint stiffness, swollen/painful finger or toe joints, tendon-insertion pain, or low-back stiffness, tell your doctor — this may call for systemic therapy (oral immunomodulators or biologics), not just nail-directed treatment. See our articles on overall psoriasis treatment and biologics.

First line: topical therapy (creams, and laser-assisted delivery)

For mild disease, or people who prefer not to be injected, topical therapy is a reasonable start. The key is getting the drug in, because — as noted — the nail plate is the biggest barrier. Elston's editorial reviews several topical strategies:

Vitamin D analog ointments (calcipotriol, ± steroid)

Calcipotriol is a vitamin D3 analog that curbs keratinocyte over-proliferation; it is a topical mainstay for psoriasis and a Taiwan-NHI-covered topical for plaque psoriasis. A calcipotriol-plus-topical-steroid combination (e.g. Daivobet ointment, Enstilar foam) is commonly used and helps some nail psoriasis (especially nail-bed types like subungual hyperkeratosis, oil-drop sign); applied to the proximal nail fold and the under-edge of the nail to maximize contact with diseased tissue. Elston also notes a study where a 20% urea + calcipotriol combination may outperform some intralesional injections (5-FU, MTX, triamcinolone) — urea softens and dissolves part of the nail-plate keratin, helping calcipotriol penetrate.

Topical methotrexate 1% gel + fractional CO2 laser-assisted delivery

Methotrexate (MTX) is an old psoriasis drug that can also be formulated topically. Elston cites data that topical MTX 1% gel has some efficacy for nail psoriasis. The problem is again penetration: to get the gel under the nail, it can be paired with fractional CO2 laser — the laser drills many micro-channels in the nail plate through which the drug penetrates. A randomized comparative study (Moftah 2024) found fractional CO2 laser + MTX 1% gel improved at least some parameters versus MTX 1% gel alone. Note this is a single-center RCT with a small sample, and the laser is a device procedure — in Taiwan such laser-assisted delivery has no nail-psoriasis NHI indication and is out-of-pocket.

The editorial also notes a study systematically comparing penetration-enhancement methods for delivering MTX into the nail: plain topical MTX, chemical penetration enhancers, nanotechnology, protein transduction domains, liquid crystalline systems, physical enhancer + laser, and intralesional injection. Overall, the topical forms had favorable safety; and for topical-refractory patients, a 25 mg/mL intralesional MTX solution worked well — which brings us to intralesional injection.

Topical option	How it works	Evidence	Taiwan coverage
Calcipotriol (± steroid combo)	Curbs keratinocyte proliferation; combo adds anti-inflammatory. Apply to nail fold / under-edge	Topical mainstay; modest nail efficacy, takes months	NHI-covered (plaque psoriasis, ≤ 30 g/week)
20% urea + calcipotriol	Urea softens keratin and aids penetration; plus calcipotriol	May outperform some intralesional injections in one comparison	Urea often compounded / self-pay; calcipotriol partly NHI
Topical MTX 1% gel	Local antiproliferative; penetration is the limit	Partial efficacy (small studies)	No nail-psoriasis indication; self-pay off-label
Fractional CO2 laser + MTX gel	Laser micro-channels in nail plate aid drug entry	Improves some parameters (Moftah 2024 single-center RCT)	Self-pay; laser is a device procedure

Advanced: intralesional injection (an off-label, self-pay option for refractory disease)

To be clear about its place: intralesional injection is not a standard first-line therapy for nail psoriasis, but an advanced option a dermatologist may consider when topicals fail and systemic therapy is unwanted or unsuitable. It has no nail-psoriasis indication under Taiwan NHI and is out-of-pocket off-label. This section summarizes observations from an editorial and small studies — it is not treatment advice.

Where it's injected, and with what

Intralesional injection delivers the drug directly to the diseased matrix or nail bed, bypassing the nail-plate barrier. The site depends on the lesion source: matrix-type lesions (pitting, deformity) are injected into the matrix beneath the proximal nail fold; nail-bed-type lesions (onycholysis, subungual hyperkeratosis) into the nail bed. Three drug classes are common: triamcinolone acetonide (a long-acting steroid), methotrexate (MTX), and 5-fluorouracil (5-FU). Elston notes that for refractory lesions he often combines topical treatment with intralesional injection of a triamcinolone-plus-MTX-or-5-FU mixture, similar to the combination injections used for keloids.

Does it hurt? Anesthesia technique

Many people flinch at injecting a nail — fingertips are genuinely sensitive. But Elston stresses there is a solution: a digital / palmar / wrist block with lidocaine and bupivacaine numbs the whole finger first, allowing painless matrix injection. These blocks are easy to learn and are the key to making intralesional injection feasible and tolerable. In other words, fear of pain alone should not be the reason to refuse evaluation — provided it is done by a clinician familiar with these anesthesia techniques.

Figure 2. Intralesional injection workflow. A digital/palmar/wrist nerve block makes injection painless; then injection is directed by lesion source — matrix-type (pitting, deformity) into the matrix beneath the proximal nail fold, nail-bed-type (onycholysis, hyperkeratosis) into the nail bed. The drug (MTX, steroid, or 5-FU) can form a slow-release depot in the matrix, with effects potentially lasting months. Site and drug choice require dermatologist judgment; this figure is for education only.

This issue's key study: Mello's pharmacokinetic findings

Elston's editorial accompanies a pharmacokinetic study by Mello et al. in the same JAAD issue. Three takeaways:

Single dose, sustained: a single periungual MTX injection induced multi-month remission of nail psoriasis — no weekly dosing needed.
Low plasma levels, slow clearance: post-injection plasma MTX compared favorably to oral/parenteral systemic dosing (no high peak), and cleared slowly, suggesting a slow-release depot at the injection site (matrix) — like a slowly releasing drug reservoir. This may be why one injection lasts months.
Safety is an important step but unsettled: the authors frame this pharmacokinetic data as an important step in establishing patient safety, since knowing plasma levels matters for counseling. But they honestly state: although plasma levels were relatively low, more study is needed to confirm whether the matrix slow-release truly has a safety profile comparable to weekly oral/parenteral MTX.

Key interpretation

The slow-release depot is the most interesting idea here: injecting into the matrix places a small reservoir that releases slowly, sustaining effect without a high plasma peak — in theory balancing efficacy and systemic safety. But both Elston and the original authors stress this is still at the exploring-cost-effective-options stage, not a settled standard — which is why this article frames it as an advanced, self-pay option for refractory disease.

The evidence is actually mixed: MTX vs steroid — which is better?

Elston is candid here: which drug to inject is not settled — the data are inconsistent.

Favoring steroid: some data show depot (long-acting) corticosteroid outperforms intralesional MTX (Kassem 2024, comparing methylprednisolone acetate vs MTX on psoriatic nails).
Favoring MTX: other data show more sustained effect with MTX (Starace 2022, a pilot study comparing intralesional MTX vs triamcinolone acetonide for nail-matrix psoriasis).
Low dose may also work: another report notes even relatively low-dose intralesional MTX may be effective (Seidel 2025, a 4-case series).

Putting these together: these are pilot studies, case series, or small comparisons whose conclusions don't fully agree. The honest conclusion is — intralesional injection may help some refractory patients, but the best drug, optimal dose, and long-term safety are all unsettled. That is why it remains an advanced option requiring individualized evaluation, not a one-size-fits-all standard.

Taiwan NHI coverage vs out-of-pocket reality

Taiwan NHI · key points

Taiwan NHI covers topicals for psoriasis, but what it covers are vitamin D analogs / retinoids, with the indication written as plaque psoriasis rather than nail-specific:

Calcipotriol topical monotherapy: for confirmed plaque psoriasis, ≤ 30 g or 30 mL per week; exceeding requires charting.
Calcipotriol + steroid combinations (e.g. Daivobet, Enstilar): for plaque psoriasis, ≤ 30 g/week; continuous use beyond 8 weeks requires detailed charting of the reason.
Topical tazarotene, calcitriol (e.g. Silkis, for < 35% body surface area): also under psoriasis topical coverage, with a 30 g/mL weekly cap.

But the advanced options discussed here have no nail-psoriasis indication under Taiwan NHI, so they are mostly out-of-pocket and off-label:

Intralesional injection (MTX / triamcinolone / 5-FU) for nail psoriasis: no such indication in the NHI dermatology-preparations chapter — self-pay off-label.
Fractional CO2 laser-assisted delivery: the laser is a device procedure with no nail-psoriasis coverage — self-pay.
Topical MTX 1% gel: not an NHI item — self-pay off-label.

Also worth distinguishing: if your psoriasis is not just in the nails but moderate-to-severe with psoriatic arthritis, systemic therapy (oral immunomodulators or biologics) follows a separate NHI coverage track (with PASI / body-surface-area / joint criteria) — a different pathway from nail-psoriasis topical treatment. Confirm actual costs and coverage in person with your dermatologist and clinic.

(NHI coverage details summarized from the National Health Insurance Administration's Drug Reimbursement Regulations, version 2026-04-23; actual coverage follows the latest NHIA announcements.)

Frequently asked questions

Q1. My nail psoriasis doesn't respond to creams — do I have to get injections?

Not necessarily. Topical failure is often about insufficient penetration rather than the drug being useless — review your technique (applying to the nail fold and under-edge, using it regularly for months) or add a penetration strategy (urea softening, laser assist). Injection (intralesional) is one advanced option when topicals still fail; whether and what to inject needs a dermatologist's assessment of your lesion type and preferences. And remember: if joint symptoms coexist, your doctor may recommend systemic therapy rather than continuing nail-directed treatment.

Q2. Does injecting the nail hurt a lot?

Fingertips are sensitive, but anesthesia solves it. Elston stresses that a digital / palmar / wrist block with lidocaine and bupivacaine allows painless matrix injection. These techniques are not hard for dermatologists to learn. So fear of pain alone is usually not a sufficient reason to forgo evaluation — provided it's done by a clinician familiar with these techniques.

Q3. How long does one injection last?

Mello et al.'s pharmacokinetic study observed that a single periungual MTX injection induced multi-month remission, possibly because the drug forms a slow-release depot in the matrix. But this is a small-study observation with wide individual variation; actual duration varies by person, lesion type, drug, and dose — there is no guarantee.

Q4. Is MTX or steroid injection better?

It's unsettled. Some studies favor depot steroid over intralesional MTX (Kassem 2024); others favor more sustained effect with MTX (Starace 2022). These are small studies with inconsistent conclusions. In practice, clinicians choose individually based on lesion type, prior response, and safety — sometimes using a mixture.

Q5. Is intralesional MTX safe? Will it harm the liver or bone marrow like oral MTX?

Mello's data show relatively low plasma MTX after injection (not as high as systemic dosing), so systemic side-effect risk is theoretically smaller. But the authors themselves stress this is only an important step in establishing safety; more study is needed to confirm whether the matrix slow-release is truly as safe long-term as weekly oral/parenteral dosing. So it cannot be called absolutely safe — a doctor must assess your situation (liver/kidney function, pregnancy/conception plans, other medications).

Q6. Are these treatments covered by Taiwan NHI?

Topical vitamin D analogs (calcipotriol, steroid combos, tazarotene, calcitriol) are NHI-covered for plaque psoriasis (with weekly dose caps). But intralesional injection, CO2 laser-assisted delivery, and topical MTX gel for nail psoriasis have no NHI indication and are self-pay off-label. Confirm costs and coverage with your clinic in person.

Q7. How do I know if it's nail psoriasis or a fungal nail?

Appearance alone can be hard to distinguish, and the two can coexist. Clues include: symmetric multi-nail involvement, pitting/oil-drop discoloration, and psoriasis elsewhere (scalp, elbows, knees). Confirming the diagnosis often needs KOH microscopy/culture, sometimes a biopsy. Don't keep self-applying antifungals for months without effect — see a dermatologist to sort it out.

Q8. Will nail psoriasis get better? How long does treatment take?

Nail psoriasis can improve, but because nails grow slowly (fingernails ~3 mm/month, toenails slower), any treatment takes several months before healthy new nail shows — judging efficacy requires patience. It is also chronic and may recur; the goal is usually control and improvement rather than a one-time cure. Regular treatment and follow-up with your doctor is the realistic expectation.

Common myths

Myth	Reality
"Deformed nails must be fungal — just use antifungals."	Nail psoriasis and fungal nails overlap and can coexist. Antifungals don't help psoriasis. When in doubt, confirm with fungal testing/biopsy.
"If creams don't work, the disease is hopeless."	Topical failure is often poor penetration. Adjust technique, add penetration aids, or consider advanced options like injection; those with arthritis may go systemic.
"Intralesional injection is standard — everyone should get it."	It's an advanced, self-pay, off-label option for refractory disease; evidence is mostly from small studies, best drug/dose unsettled — needs individualized assessment.
"Injecting a nail must be unbearably painful."	Digital/palmar/wrist nerve blocks allow painless injection — the key technique that makes this option tolerable.
"Nail psoriasis is just cosmetic — no big deal."	Nail psoriasis is closely linked to psoriatic arthritis and may warn of joint involvement; seek evaluation if joint symptoms appear.

Clinical pearls for colleagues

For Clinicians

Lesion localization dictates injection site: matrix signs (pitting, leukonychia, crumbling) → matrix (beneath proximal nail fold); nail-bed signs (oil-drop, onycholysis, subungual hyperkeratosis, splinter haemorrhage) → nail bed. Map signs to anatomy first, then choose the entry point.
Anesthesia is the feasibility key: lidocaine + bupivacaine digital/palmar/wrist blocks make matrix injection tolerable; bupivacaine prolongs post-procedure analgesia. Elston calls these "easy to learn."
Drug-choice evidence diverges: Kassem 2024 favors methylprednisolone acetate over intralesional MTX; Starace 2022 pilot favors more sustained MTX effect; Seidel 2025 (4 cases) suggests low-dose MTX may also work. No single best answer — individualize.
New PK data (Mello): single periungual MTX → multi-month remission; relatively low plasma levels, slow clearance, supporting a matrix-depot hypothesis. Useful for counseling, but the authors state more study is needed before claiming long-term safety equals weekly oral/parenteral.
Don't skip systemic assessment: nail psoriasis is a risk marker for psoriatic arthritis. For moderate-severe disease or joint symptoms, systemic therapy (oral or biologic) is the backbone; topical/intralesional is adjunctive.
Taiwan coverage framing: topical vitamin D analogs/retinoids are NHI-covered (plaque psoriasis, weekly caps); intralesional injection / laser-assist / topical MTX gel have no nail-psoriasis coverage and are self-pay off-label — discuss informed consent and cost upfront.

Takeaway

Nail psoriasis is hard to treat because the drug can't get in, the lesion sits deep, and nails grow slowly. Elston's June 2026 JAAD editorial lays out the spectrum from topical (vitamin D analog ointments, 20% urea + calcipotriol, topical MTX gel with fractional CO2 laser-assisted delivery) to intralesional injection (MTX, steroid, 5-FU), and solves the "injections hurt" concern with anesthesia (digital/palmar/wrist nerve blocks). The companion Mello pharmacokinetic study adds the latest observation — a single periungual MTX injection induced multi-month remission with low plasma levels and slow clearance, suggesting a matrix slow-release depot. But the evidence for these advanced approaches is mostly from small, diverging studies; the best drug and long-term safety are unsettled, and in Taiwan they have no nail-psoriasis NHI indication and are self-pay off-label. The pragmatic path for patients: use topical therapy correctly and fully first, watch for joint warning signs, then discuss with a dermatologist whether advanced or systemic therapy is needed — with options, evidence strength, and costs all on the table.

This article is educational and a research summary based on Elston (2026 JAAD editorial) and its cited references; it cannot replace in-person medical care. Diagnosis, medication (topical, intralesional, laser, systemic), and NHI/self-pay choices for nail psoriasis must be discussed with a board-certified dermatologist and decided per your individual situation. This site does not run medical advertising, does not recommend specific clinics/hospitals/drugs/procedures, and accepts no sponsorship or paid promotion.

References

Elston DM. Topical and intralesional therapy for nail psoriasis. J Am Acad Dermatol. 2026;94(6):1653-1654. doi:10.1016/j.jaad.2026.02.004. https://doi.org/10.1016/j.jaad.2026.02.004
Hassan Moftah N, Helmy WHA, Mohamed Elbakry A, Mohammed Gamal-Edeen A, Al-Sayed Al-Kady N. Combined fractional CO2 laser 10,600 nm with methotrexate 1% gel versus methotrexate 1% gel alone in the treatment of nail psoriasis: a randomized comparative study. Arch Dermatol Res. 2024;317(1):153. doi:10.1007/s00403-024-03636-3. https://doi.org/10.1007/s00403-024-03636-3
Chaiyabutr C, Punnakitikashem P, Silpa-Archa N, Wongpraprarut C, Chularojanamontri L. The anti-psoriatic efficacy and safety profile of topical and intralesional methotrexate: a literature review. Clin Cosmet Investig Dermatol. 2022;15:2253-2274. doi:10.2147/CCID.S380218. https://doi.org/10.2147/CCID.S380218
Seidel A, Rigatti M, de Farias DC, Bald AP, Schmitz JRG. Treatment of nail psoriasis with intralesional methotrexate: report of four cases demonstrating an effective and safe approach with lower doses. An Bras Dermatol. 2025;100(1):211-213. doi:10.1016/j.abd.2024.05.001. https://doi.org/10.1016/j.abd.2024.05.001
Kassem R, Gupta AK, Bamimore MA, et al. Effect of the intralesional forms of methylprednisolone acetate and methotrexate on psoriatic nails. Skinmed. 2024;22(1):35-39.
Starace M, Alessandrini A, Iorizzo M, et al. A pilot study of intralesional methotrexate injections versus triamcinolone acetonide in patients affected by nail matrix psoriasis. Clin Exp Dermatol. 2022;47(6):1165-1168. doi:10.1111/ced.15110. https://doi.org/10.1111/ced.15110
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