Mechlorethamine
Mechlorethamine is an alkylating drug used topically to treat Stage IA and IB mycosis fungoides-type cutaneous T-cell lymphoma (a type of skin lymphoma).
🧬 Where this information comes from Click to expand
The clinical label records used on this page are FDA-filed Structured Product Labeling (SPL) retrieved through openFDA. We identified 1 clinical label set within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. Forms, routes, brands, labelers, strengths, and NDC product-record counts are built separately from matching FDA National Drug Code Directory records. The linked DailyMed document is a representative official source for verification, not the page’s only clinical source. View the linked label on DailyMed →
📖 Mechlorethamine: Patient Information Guide
A plain-language walkthrough of Mechlorethamine — what it treats, how it works, how it’s taken, side effects, warnings and interactions. Tap any section to expand it.
🎯What it's used for▾
Mechlorethamine is an alkylating drug approved for topical treatment of a specific type of skin lymphoma. Its supported use is product-specific:
- Valchlor (mechlorethamine gel): Treats Stage IA and IB mycosis fungoides-type cutaneous T-cell lymphoma — an early-stage form of lymphoma that primarily involves the skin — in patients who have already received other skin-directed treatments.
⚙️How it works▾
Mechlorethamine is an alkylating agent, sometimes called a nitrogen mustard. It works by chemically bonding to DNA inside rapidly dividing cells, disrupting their ability to replicate. This targets the abnormal lymphoma cells growing in the skin and helps slow or stop the disease. When Valchlor is applied to the skin, it works locally — studies showed no detectable levels of mechlorethamine entering the bloodstream after topical application.
💊How it's taken▾
Valchlor gel is applied topically once daily as a thin film to affected areas of the skin. It should be applied to completely dry skin — at least 4 hours before or 30 minutes after showering or washing. Allow the treated area to dry for 5–10 minutes before covering with clothing. Moisturizers may be applied 2 hours before or 2 hours after application. Do not use occlusive (airtight) dressings over treated areas. Always follow your prescriber's specific instructions; if your skin reacts severely, your doctor may reduce the frequency or pause treatment.
🤒Side effects — in detail▾
The most common side effects with Valchlor involve the skin:
- Dermatitis (skin redness, swelling, inflammation) — the most common reaction, occurring in more than half of patients
- Itchiness (pruritus)
- Bacterial skin infection
- Skin blistering or ulceration
- Skin darkening (hyperpigmentation)
Severe skin reactions — including bad blistering, open sores, or moderately-severe dermatitis — may require pausing or stopping treatment. Call your doctor right away if these develop. A small number of patients also developed non-melanoma skin cancer during or after treatment, so ongoing skin monitoring is important.
⚠️Warnings & precautions▾
- Eye and mucosal injury: If Valchlor contacts your eyes, it can cause severe pain, burns, and potentially permanent blindness. Rinse immediately with large amounts of water for at least 15 minutes and get urgent medical care. Contact with the mouth or nasal lining can also cause painful ulcers.
- Skin reactions (dermatitis): More than half of patients experienced dermatitis. The face, genitals, anus, and skin folds are especially vulnerable. Monitor your skin and follow your doctor's instructions about dose adjustments.
- Non-melanoma skin cancer: A small percentage of patients developed non-melanoma skin cancer during or after treatment. Skin monitoring during and after treatment is important.
- Embryo-fetal toxicity: Mechlorethamine may cause serious harm to a developing baby. Women should avoid becoming pregnant during treatment; both male and female patients should use effective contraception.
- Secondary exposure: People other than the patient should not touch Valchlor. Caregivers must wear nitrile gloves when applying it and wash hands immediately afterward.
- Flammable: Valchlor is an alcohol-based gel. Avoid fire, flame, and smoking until the gel has completely dried on the skin.
🔀What it interacts with▾
No formal drug interaction studies have been conducted with Valchlor. Because the drug is not detectably absorbed into the bloodstream after topical use, systemic drug interactions are considered unlikely. Discuss all medications, supplements, and skin products you use with your doctor or pharmacist.
This is not a complete list of interactions. Always talk with your doctor or pharmacist before starting, stopping, or changing any medication.
📋Before taking it▾
- Severe allergy to mechlorethamine: Valchlor is contraindicated (must not be used) if you have a known severe allergic reaction — including anaphylaxis — to mechlorethamine.
- Pregnancy: Mechlorethamine may cause fetal harm, including birth defects. Do not use Valchlor if you are pregnant, and use effective contraception during treatment.
- Breastfeeding: Do not breastfeed while using Valchlor; the drug could expose your infant through skin contact or systemic transfer.
- Males of reproductive potential: Use effective contraception during treatment, and use a barrier method to prevent direct exposure of reproductive organs to the gel.
- Children: Safety and effectiveness in pediatric patients have not been established.
- Older adults (65+): Older patients may experience more skin-related side effects and are more likely to discontinue treatment. Close monitoring is recommended.
- Fertility: Mechlorethamine may impair fertility in both males and females; whether this is reversible is not known.
🔬Pharmacokinetics — how your body processes it▾
When Valchlor gel is applied to the skin, systemic absorption is not detectable. In clinical studies, patients using mechlorethamine gel at 0.016% had no measurable drug levels in their blood on the day of application or at one month. Patients using a higher concentration (0.032%) also had no measurable levels of mechlorethamine or its breakdown products after 2, 4, or 6 months of treatment. This means the drug acts locally in the skin with no meaningful amount entering the bloodstream.
📦How to store it▾
store in the freezer at -13°F to 5°F (-25°C to -15°C). refrigerated storage is required once dispensed.
📄 Written from Mechlorethamine’s FDA-approved label information, summarized in plain language with AI, and reviewed by our pharmacy team before publication. Every point is grounded in that labeling — nothing is invented. How we use AI →
Supplements & herbs that interact with Mechlorethamine
17 supplements and herbal products have documented interactions with Mechlorethamine in the licensed clinical database we use. Most are manageable — but your pharmacist should know about everything you take, including vitamins and herbals.
- Major · 1
- Moderate · 7
- Minor · 9
Educational information from a licensed clinical database (Natural Medicines) — see our data sources & update cadence. Not medical advice: an interaction being documented does not mean it will happen to you; do not start or stop medications or supplements without professional guidance.
🩺 Pharmacist Counseling Corner
Quick, plain-English answers to the questions patients ask most about Mechlorethamine — the kind of thing our pharmacy team would talk through with you at the counter.
What exactly is Valchlor being used to treat? ▾
How do I apply Valchlor correctly, and are there any special steps I need to follow? ▾
What side effects should I watch out for? ▾
What happens if Valchlor gets in my eyes or mouth? ▾
Is it safe to use Valchlor if I'm pregnant or trying to get pregnant? ▾
Is it safe for people around me to be near Valchlor? ▾
Is Mechlorethamine available over the counter? ▾
When was Mechlorethamine first available? ▾
Who makes Mechlorethamine? ▾
💬 Answers drafted from Mechlorethamine’s FDA-approved label information, summarized in plain language with AI, and reviewed by our pharmacy team before publication. Grounded in that labeling — nothing is made up. How we use AI →
🧰 Keep exploring
💊 How Mechlorethamine comes
Mechlorethamine is available in 1 form. Different forms and brands can have different approved uses, doses, schedules, and directions. Follow the instructions for your exact product, and do not switch forms without guidance from your prescriber or pharmacist.
Topical cream, ointment or gel
How this form is used
- Valchlor is used to treat Stage IA and IB mycosis fungoides-type cutaneous T-cell lymphoma in patients who have received prior skin-directed therapy
- Valchlor: Apply a thin film once daily to affected areas of dry skin
- Valchlor: Apply immediately or within 30 minutes of removing from the refrigerator, then return it to the refrigerator right after use
- Valchlor: Apply to skin that is completely dry — at least 4 hours before or 30 minutes after showering or washing; allow treated area to dry 5–10 minutes before covering with clothing
- Valchlor: Patients must wash hands thoroughly with soap and water after applying; caregivers must wear disposable nitrile gloves during application
📊 Mechlorethamine across the U.S. market
How Mechlorethamine appears in the FDA’s National Drug Code Directory — including its dosage forms, strengths, brand names, manufacturers, and FDA-listed product records. These are directory records, not sales or prescription volume.
Also listed with the FDA, not a patient dose form: Powder (1) — bulk drug substance sold to compounders/manufacturers and multi-item kits. These aren’t counted in the dose-form total above.
Share of FDA-listed product records by manufacturer — FDA National Drug Code Directory. Record counts are not sales or prescription volume.
📈 How widely Mechlorethamine is used
A general measure of how commonly Mechlorethamine is prescribed, based on Medicaid — one of the largest public drug programs. The figure below is prescriptions filled in Q1–Q4 2025, summed across every form and brand of the drug.
Think of this as a proxy for how widely Mechlorethamine is used, drawn from freely available public data. Medicaid is just one program — these numbers don’t include Medicare, other government coverage, or commercial and cash-pay prescriptions, so real-world use is higher than what’s shown here.
How commonly is Mechlorethamine prescribed? Of the 1,596 medications we measure, Mechlorethamine ranks #1,489 by Medicaid prescriptions — more than 7% of them.
Utilization by Mechlorethamine product
Pick a product to see its own Medicaid numbers. Each chip is one clinical product — a specific strength & dosage form as defined by RxNorm — with brand-name and generic versions combined.
mechlorethamine 0.00016 MG/MG Topical Gel
Summed across the 1 of 1 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 1437711
Shares are of the Medicaid prescriptions shown here. Product grouping follows RxNorm (the National Library of Medicine’s drug terminology), so “one product” means one strength & dosage form regardless of manufacturer. Dollar figures are gross Medicaid reimbursement before mandatory rebates — rebates (often large, especially for brand-name drugs) are confidential, so actual net cost to Medicaid is lower than shown.
Source: Medicaid State Drug Utilization Data (CMS), aggregated by generic ingredient — summed across every NDC (all brands, strengths, salt forms and dosage forms) of Mechlorethamine, and across all states and both fee-for-service and managed-care claims. A general popularity signal; it excludes Medicare, commercial insurance and cash prescriptions, so it is not total U.S. use. Based on the 1 of 1 listed Mechlorethamine NDCs with Medicaid activity.
🔍 Compare Mechlorethamine products
A representative set of FDA-listed product records for Mechlorethamine — across manufacturers, strengths, and dosage forms, grouped by form with each product’s manufacturer and how the FDA approved it. The same medicine may be made and packaged by different companies, so a single drug can have many directory entries. (It’s also why a refill can look different — a new shape, color, or box — even though it contains the same medication.)
| Strength | Route | Manufacturer / Labeler | Category ⓘ | Details |
|---|---|---|---|---|
| 💊Topical cream, ointment or gel | ||||
| 0.012 g/60 g | Topical | Helsinn Therapeutics (U.S.), Inc. × 3 listings | NDA | View NDC → |
| 💊Bulk drug substance | ||||
| 1 g/g | — | Sigma-Aldrich Corporation | BULK INGREDIENT | View NDC → |
Showing 4 of 4 products — FDA National Drug Code Directory. See every product, package size and price: browse all 4 Mechlorethamine NDCs →
📈 What people report — real-world data (FDA FAERS)
After a medicine reaches the market, patients, doctors and drugmakers can send the FDA reports of problems they think may be linked to it. Here’s what’s been reported for Mechlorethamine — a signal of what to watch for, not proof the drug caused it.
Source: openFDA, from the FDA Adverse Event Reporting System (FAERS). These are voluntary reports — they don’t prove the drug caused the effect, and counts reflect how often something was reported, not how often it actually happens. Reports also often name the very problem the medicine is taken for — a common reason to file one is that the drug didn’t help — so for a pain reliever you may see “pain” high on the list; that points to why the report was filed, not to the drug causing the symptom. This counts every report that lists Mechlorethamine in any role, so the total runs higher than the FDA’s official dashboard, which counts only cases where the drug is the suspect. For the authoritative figures, see the FDA FAERS Public Dashboard. Always talk to your pharmacist or doctor.
🏛️ The road to your pharmacy
How Mechlorethamine went from FDA review to the pharmacy shelf — the key milestones in its regulatory journey.
Source: Drugs@FDA.
🚨 Recall history
A recall is when a specific batch of a medicine is pulled from the market — usually a manufacturing issue, not a problem with the drug itself. Class I is most serious, Class III least.
Source: openFDA drug enforcement (recall) reports.
RxNorm Concept Web — From Ingredient to Every Form and Strength
This page starts with one ingredient concept (IN). The branches below show its dose-form concepts (SCDF), then the available clinical drug and strength concepts (SCD). Combination products remain separate concepts with their own pages.
RxCUI 6674 1 dose form · 1 strength
-
Dose form (SCDF) Topical Gel RxCUI 1437554In current FDA listingsClinical drug / strength (SCD) 0.00016 MG/MGRxCUI 1437711
Look up RxCUI 6674 in the RxCUI Atlas →
RxNorm is the U.S. National Library of Medicine’s normalized drug vocabulary. Its concept hierarchy can include forms that are not currently marketed; the status on each branch compares that concept with current FDA listings. RxCUIs identify vocabulary concepts, not individual packages or manufacturers.
📦 Supply & shortage status
Whether Mechlorethamine is in short supply in the U.S. right now, plus any shortage history the FDA has on record. A shortage usually reflects a manufacturing or demand issue — not a safety problem with the drug.
Source: openFDA, from the FDA Drug Shortages database.
🏷️ Sold under these brand names
🏭 Manufacturers & labelers
RxNorm drug class
Mechlorethamine belongs to the Alkylating Drug class.
Classified by RxNorm RxClass — the U.S. National Library of Medicine's standardized drug-classification service (Established Pharmacologic Class from the FDA, the ATC drug family from the WHO, and mechanism of action). Reference only, not medical advice.
🔬 Where this comes from
Core label, product, RxNorm, safety, and utilization data on this page come from the sources identified below. AI-written, editorial, and licensed sections are labeled separately.
How we combine label and product data
HelloPharmacist combines public FDA and NLM records; we don’t author the underlying clinical facts. We identified 1 FDA-filed SPL label set within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. The representative label is the starting point for the displayed reference monograph; the 12 largest stored in-scope SPL records, which may include that representative, are compared section by section, and the longest available version of each section is retained. Forms, routes, brands, labelers, product-listed strengths, and product-record counts are aggregated separately from ingredient-matched FDA NDC Directory records; package records listed above are associated with the linked SPL; and the normalized concept hierarchy comes from NLM RxNorm.
For canonical ingredient pages, bounded product-attributed indication and administration excerpts may be added to the AI evidence, and the generator is instructed to preserve available product, brand, route, and form qualifiers instead of treating one label as universal. Where a section is identified as AI-written, its plain-language text is generated from bounded label evidence. New draft drug pages remain in the admin review queue before first publication. Helsinn Therapeutics (U.S.), Inc. is the representative DailyMed label linked for verification and dates; it is not the sole source used for the page.
This is general education, not medical advice — always consult your doctor or pharmacist about your medications and any medical condition. For the exact wording of the linked representative label, view that label on DailyMed; some displayed composite sections may come from other in-scope SPL labels. Learn how we use AI and our data sources & update cadence.