Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
ALA-SCALP vs A-HYDROCORT
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
ALA-SCALP (aminolevulinic acid) is a photosensitizer precursor that is converted intracellularly to protoporphyrin IX (Pp IX), which accumulates in cells with increased heme synthesis, such as rapidly dividing cells. Upon exposure to blue light (BLU-U®), Pp IX produces reactive oxygen species, leading to cellular damage and apoptosis of targeted cells.
Hydrocortisone is a corticosteroid hormone that binds to glucocorticoid receptors, modulating gene expression to suppress inflammation, inhibit immune response, and regulate metabolism.
Treatment of minimally to moderately thick actinic keratoses of the scalp (Grade 1 or 2) in immunocompetent patients,Off-label: other photosensitivity disorders
Adrenocortical insufficiency (primary and secondary),Congenital adrenal hyperplasia,Inflammatory conditions (e.g., rheumatoid arthritis, ulcerative colitis),Allergic reactions (severe),Asthma exacerbations,Dermatologic disorders (topical use),Ophthalmic inflammation (ophthalmic use)
Topical application of a 5% solution to the scalp twice daily.
Adrenal insufficiency: oral 20-30 mg/day in divided doses; inflammatory conditions: 5-60 mg/day oral; IV/IM: hydrocortisone sodium succinate 50-100 mg every 4-6 hours.
Not applicable; topical ALA-SCALP is not significantly absorbed systemically. After systemic absorption from photodynamic therapy, terminal half-life is approximately 1 hour due to rapid metabolism.
Terminal half-life: 1.5-2 hours (cortisol); clinical effect persists 8-12 hours due to glucocorticoid receptor binding
ALA is metabolized intracellularly via the heme biosynthesis pathway to protoporphyrin IX (Pp IX).
Primarily hepatic via CYP3A4 and other CYP450 enzymes, with reduction in the A-ring to inactive metabolites (e.g., tetrahydrocortisol).
Primarily renal elimination of metabolites; <1% excreted unchanged in urine. Biliary/fecal excretion is negligible.
Renal (primarily as metabolites, <1% unchanged); biliary/fecal (<5%)
Not characterized; systemic levels are negligible after topical administration.
90-95% bound to corticosteroid-binding globulin (CBG) and albumin
Not applicable for topical route. If systemic exposure occurs, Vd is approximately 0.5 L/kg, consistent with distribution into total body water.
0.5-0.8 L/kg; represents distribution into total body water, higher in obesity
Topical: Systemic bioavailability is minimal (<1%) due to poor percutaneous absorption and rapid local metabolism.
Oral: 96% (well absorbed); IM/IV: 100%; topical: minimal systemic absorption (<1% with intact skin)
No dose adjustment required for renal impairment.
No specific adjustment required; monitor fluid/electrolytes in severe renal impairment.
No dose adjustment required for hepatic impairment.
Dose reduction may be necessary in severe hepatic impairment; caution as metabolism is hepatic.
Safety and efficacy in pediatric patients have not been established.
Doses are weight-based; for adrenal insufficiency: 0.5-0.75 mg/kg/day in divided doses; for anti-inflammatory: 0.5-10 mg/kg/day.
No specific dose adjustment recommended; use with caution due to potential increased sensitivity.
Use lowest effective dose; monitor for osteoporosis, hypertension, and glucose intolerance.
No FDA black box warning.
None.
Photosensitivity: avoid exposure to sunlight or bright indoor light (e.g., examination lamps, operating room lamps) for at least 40 hours post-application.,Application site reactions: severe stinging, burning, erythema, and edema may occur.,Use sun-protective measures (e.g., wide-brimmed hat, sunscreen) after treatment.,Do not apply to eyes or mucous membranes.
Immunosuppression and increased infection risk,Adrenal suppression with prolonged use,Cushing's syndrome with chronic use,Osteoporosis with long-term use,GI perforation risk in inflammatory bowel disease,Growth suppression in children,Fetal harm (category C),Ocular effects (cataracts, glaucoma),Fluid and electrolyte disturbances
Hypersensitivity to aminolevulinic acid or any component of the formulation,Cutaneous photosensitivity at wavelengths of 400-450 nm,Porphyria
Systemic fungal infections,Hypersensitivity to hydrocortisone or any component,Administration of live or live-attenuated vaccines (relative),Herpes simplex keratitis (topical ophthalmic use),Peptic ulcer disease (relative),Uncontrolled hypertension (relative)
No known food interactions. No dietary restrictions required.
No specific food interactions. However, high-sodium foods may exacerbate fluid retention; a low-sodium diet is recommended if edema occurs. Grapefruit juice does not significantly affect hydrocortisone. Avoid alcohol due to additive gastric irritation.
No evidence of teratogenicity; topical application with minimal systemic absorption. First trimester: unlikely risk. Second/third trimester: no known fetal risks from maternal use.
Hydrocortisone is a corticosteroid. Use during first trimester is associated with increased risk of oral clefts (odds ratio 1.5-3.0). Second and third trimester use may cause fetal adrenal suppression, growth restriction, and premature birth. Risk of premature rupture of membranes and intrauterine growth restriction increases with prolonged use.
Minimal systemic absorption; unlikely to appear in breast milk. M/P ratio not established. Considered compatible with breastfeeding.
Hydrocortisone is excreted into breast milk in low concentrations. M/P ratio approximately 0.4-1.0. Doses up to 20 mg/day are considered compatible with breastfeeding. Higher doses may suppress infant adrenal function; monitor infant for growth and adrenal suppression.
No dosage adjustment required; pharmacokinetics unlikely altered due to topical route.
Due to increased clearance and protein binding changes, doses may need to be increased by 50-100% in the second and third trimesters. Monitor clinical response and adjust dose accordingly. Stress doses (e.g., 50-100 mg IV) should be given during labor and delivery.
ALA-SCALP is a topical aminolevulinic acid preparation used for photodynamic therapy of actinic keratoses on the scalp. Must be applied by a healthcare professional. Avoid sun exposure to treated area for 48 hours post-application due to photosensitivity. Do not apply to eyes or mucous membranes. Lesions should be prepped by gentle removal of scales and crusts. Use with a compatible light source (blue light). Burning and stinging during light exposure is common; consider pain management strategies.
For acute adrenal insufficiency, give IV bolus of 100 mg hydrocortisone followed by 100 mg every 8 hours. Taper to oral replacement over days. In septic shock, stress-dose hydrocortisone (200 mg/day) may be used if vasopressor-dependent. Monitor for hyperglycemia, hypokalemia, and immunosuppression. Abrupt discontinuation can cause adrenal crisis.
This medication is applied by your doctor to treat precancerous spots on your scalp.,After application, you will need a special light treatment (photodynamic therapy).,Avoid sunlight and bright indoor light on the treated area for 48 hours after the procedure.,You may experience temporary redness, swelling, scaling, or discomfort at the treatment site.,Use sunscreen and protective clothing when going outdoors during the photosensitivity period.,Do not wash the treated area for at least 4 hours after the solution is applied.,Contact your doctor if you experience severe pain, blistering, or signs of infection.
Take exactly as prescribed; do not stop suddenly without doctor's guidance.,Carry a medical alert card or bracelet indicating you take hydrocortisone.,Report signs of adrenal crisis: severe weakness, dizziness, nausea, vomiting, abdominal pain.,During illness or stress (e.g., surgery, infection), dose may need temporary increase; contact your doctor.,Avoid live vaccines during therapy.,Monitor for weight gain, swelling, mood changes, or high blood sugar symptoms (increased thirst, urination).
No interactions on record
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about ALA-SCALP vs A-HYDROCORT, answered by our medical review team.
ALA-SCALP is a Topical Corticosteroid that works by ALA-SCALP (aminolevulinic acid) is a photosensitizer precursor that is converted intracellularly to protoporphyrin IX (Pp IX), which accumulates in cells with increased heme synthesis, such as rapidly dividing cells. Upon exposure to blue light (BLU-U®), Pp IX produces reactive oxygen species, leading to cellular damage and apoptosis of targeted cells.. A-HYDROCORT is a Corticosteroid that works by Hydrocortisone is a corticosteroid hormone that binds to glucocorticoid receptors, modulating gene expression to suppress inflammation, inhibit immune response, and regulate metabolism.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between ALA-SCALP and A-HYDROCORT depend on the specific clinical indication. These are agents from distinct pharmacological classes and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of ALA-SCALP is: Topical application of a 5% solution to the scalp twice daily.. The standard adult dose of A-HYDROCORT is: Adrenal insufficiency: oral 20-30 mg/day in divided doses; inflammatory conditions: 5-60 mg/day oral; IV/IM: hydrocortisone sodium succinate 50-100 mg every 4-6 hours.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between ALA-SCALP and A-HYDROCORT in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. ALA-SCALP is classified as Category C. No evidence of teratogenicity; topical application with minimal systemic absorption. First trimester: unlikely risk. Second/third trimester: no known fetal risks from maternal use.. A-HYDROCORT is classified as Category C. Hydrocortisone is a corticosteroid. Use during first trimester is associated with increased risk of oral clefts (odds ratio 1.5-3.0). Second and third trimester use may cause fetal. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.