Mechlorethamine
Mechlorethamine (also called nitrogen mustard) is a chemotherapy-type drug applied to the skin to treat early-stage mycosis fungoides-type cutaneous T-cell 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 (nitrogen mustard, brand Valchlor) is a specialist chemotherapy gel for early-stage (Stage IA and IB) mycosis fungoides-type cutaneous T-cell lymphoma, a lymphoma that starts in the skin, in people who have already had other skin-directed therapy. It is an alkylating agent that slows or stops fast-multiplying lymphoma cells, and one of the oldest cancer drugs, on the U.S. market since about 1949. Skin irritation and itching are very common, especially on the face, genitals and skin folds. The real danger is contact, since the gel can severely injure the eyes, even causing blindness, and ulcerate the mouth or nose, so keep it away from other people.
Clinical pearls
- If the gel gets in your eyes, rinse for at least 15 minutes and get emergency care, and rinse well after any mouth or nose contact.
- Caregivers who apply it should wear disposable nitrile gloves, and you should wash your hands well afterward.
- The gel is alcohol-based and flammable, so avoid fire, flame and smoking until it has dried.
- Have your skin checked during and after treatment, since non-melanoma skin cancer can appear, even on untreated skin.
Patient information guide A plain-language walkthrough of Mechlorethamine, written from its FDA label.
What Mechlorethamine is used for
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Mechlorethamine is used on the skin for one condition in the supported product.
- Valchlor (topical gel) treats Stage IA and IB mycosis fungoides-type cutaneous T-cell lymphoma in people who have already had skin-directed therapy.
How Mechlorethamine works
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Mechlorethamine, also known as nitrogen mustard, is an alkylating agent. It slows down cells that grow and divide quickly. That includes the lymphoma cells in the skin.
Mechlorethamine dosage
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Valchlor is for use on the skin only. It is generally applied as a thin film once daily to affected areas.
- Apply within 30 minutes of taking it out of the refrigerator. Put it back right away.
- Apply to completely dry skin, at least 4 hours before or 30 minutes after showering or washing.
- Let the area dry 5 to 10 minutes before putting on clothes.
- Moisturizers can be used 2 hours before or after application.
- Do not use occlusive dressings over treated skin.
- If skin ulcers, blisters, or moderately severe or severe dermatitis occur, treatment is stopped. It may later be restarted less often if your skin improves.
Follow your prescriber's instructions and the label.
Dosing details from the FDA-approved label
From the Mechlorethamine prescribing information (“Dosage and Administration”). Doses are set by your prescriber for your product, condition, kidney function and age — never change a dose on your own.
- Topical dermatological use (affected areas of the skin)
- Apply a thin film of VALCHLOR gel once daily to affected areas of the skin
- Stop treatment for any grade of skin ulceration, blistering, or moderately-severe or severe dermatitis (i.e., marked skin redness with edema). Upon improvement, can be restarted at a reduced frequency of once every 3 days; if tolerated for at least one week, increase to every other day for at least one week and then to once daily if tolerated.
Read the label’s full dosing text
2 DOSAGE AND ADMINISTRATION For topical dermatological use only ( 2.1 ). Apply a thin film once daily to affected areas of the skin ( 2.1 , 2.2 ). 2.1 Dosing and Dose Modification For Topical Dermatological Use Only Apply a thin film of VALCHLOR gel once daily to affected areas of the skin. Stop treatment with VALCHLOR for any grade of skin ulceration, blistering, or moderately-severe or severe dermatitis (i.e., marked skin redness with edema) [ see Warnings and Precautions ( 5.3 ) ]. Upon improvement, treatment with VALCHLOR can be restarted at a reduced frequency of once every 3 days. If reintroduction of treatment is tolerated for at least one week, the frequency of application can be increased to every other day for at least one week and then to once daily application if tolerated. 2.2 Application Instructions VALCHLOR is a cytotoxic drug. Follow applicable special handling and disposal procedures. 1 Patients must wash hands thoroughly with soap and water after handling or applying VALCHLOR. Caregivers must wear disposable nitrile gloves when applying VALCHLOR to patients and wash hands thoroughly with soap and water after removal of gloves. If there is accidental skin exposure to VALCHLOR, caregivers must immediately wash exposed areas thoroughly with soap and water for at least 15 minutes and remove contaminated clothing [ see Warnings and Precautions ( 5.2 ) ]. Patients or caregivers should follow these instructions when applying VALCHLOR: Apply immediately or within 30 minutes after removal from the refrigerator. Return VALCHLOR to the refrigerator immediately after each use. Apply to completely dry skin at least 4 hours before or 30 minutes after showering or washing. Allow treated areas to dry for 5 to 10 minutes after application before covering with clothing. Emollients (moisturizers) may be applied to the treated areas 2 hours before or 2 hours after application. Do not use occlusive dressings on areas of the skin where VALCHLOR was applied. Avoid fire, flame, and smoking until VALCHLOR has dried [ see Warnings and Precautions ( 5.6 ) ].
Read the full Dosage and Administration section on DailyMed →
Mechlorethamine side effects
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The most common side effects involve the skin.
Common side effects
- Skin irritation or inflammation (dermatitis)
- Itching
- Bacterial skin infection
- Skin ulcers or blisters
- Darkening of the skin (hyperpigmentation)
- Dermatitis (skin irritation and inflammation) was the most common, in about 56% of patients in the trial.
- Skin ulceration or blistering
When to get medical help
- Get medical help right away if the gel gets in your eyes. Rinse for at least 15 minutes, then get immediate medical care.
- Rinse for at least 15 minutes and get medical advice right away if it touches your mouth or nose.
- Call your doctor if you develop skin ulcers, blisters, or marked redness with swelling. Treatment must be stopped.
- Call your doctor about signs of skin infection or worsening irritation.
- Report any new skin growths. Non-melanoma skin cancer can occur, even on untreated skin.
- Seek emergency care for signs of a severe allergic reaction, including anaphylaxis.
Contact your doctor promptly for blisters, ulcers, severe redness or swelling, or signs of infection. Seek emergency help for eye exposure or a severe allergic reaction.
Mechlorethamine warnings and precautions
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- Eye and mucous membrane injury: Eye exposure can cause pain, burning, light sensitivity, blurred vision, and blindness. Rinse for at least 15 minutes and get immediate medical care. Mouth or nose contact can cause painful ulcers.
- Exposure of others: Other people should avoid skin contact. Risks include dermatitis, mucosal injury, and secondary cancers.
- Dermatitis: Moderately severe or severe in 23% of patients. Face, genitals, anus, and skin folds are at higher risk.
- Non-melanoma skin cancer: Seen in some patients, including on untreated skin. Skin should be monitored during and after treatment.
- Pregnancy: May cause fetal harm.
- Flammable: The gel is alcohol-based.
Mechlorethamine interactions
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Interactions are not expected to be a major concern.
- No drug interaction studies have been done with Valchlor.
- Systemic exposure has not been seen with skin use, so systemic drug interactions are not likely.
Interactions listed in the FDA-approved label
From the Mechlorethamine prescribing information (“Drug Interactions”): what the manufacturer studied or reported to the FDA.
No drug interaction studies have been performed with VALCHLOR. Systemic exposure has not been observed with topical administration of VALCHLOR; therefore, systemic drug interactions are not likely.
Read the label’s full interactions text
7 DRUG INTERACTIONS No drug interaction studies have been performed with VALCHLOR. Systemic exposure has not been observed with topical administration of VALCHLOR; therefore, systemic drug interactions are not likely.
Not a complete list. The label covers the interactions the manufacturer studied or reported, and our own interaction database does not cover every medicine either. Bring your full medication list, including vitamins and herbal products, to your pharmacist.
Before taking Mechlorethamine
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- Do not use if you have had a severe allergic reaction to mechlorethamine.
- Pregnancy: it may harm an unborn baby. Women who could become pregnant should use effective contraception, including a barrier method.
- Men with female partners who could become pregnant should use effective contraception.
- Do not breastfeed during treatment.
- It may affect fertility in men and women, and whether this reverses is unknown.
- Children: safety and effectiveness have not been established.
- Adults 65 and older: more skin reactions and more discontinuations were seen, and fewer responded to treatment in the trial.
How your body processes Mechlorethamine
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Valchlor was not detectable in the blood after being applied to the skin. In studies of 16 and 15 patients, no measurable mechlorethamine was found in blood samples. This is why systemic drug interactions are not likely.
How to store Mechlorethamine
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store in the freezer at -13°F to 5°F (-25°C to -15°C). refrigerated storage is required once dispensed.
Written from the FDA-approved label with AI and reviewed by our pharmacy team. 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.
Mechlorethamine: pharmacist answers to common questions
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 is Valchlor used for?
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How do I apply it?
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Can my family help me put it on?
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What side effects should I expect?
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What if it gets in my eyes or mouth?
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Is it safe in pregnancy or while breastfeeding?
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Is Mechlorethamine available over the counter?
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When was Mechlorethamine first available?
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Answers drafted from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →
More about Mechlorethamine on HelloPharmacist
Mechlorethamine forms and strengths (how it 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 on the skin for Stage IA and IB mycosis fungoides-type cutaneous T-cell lymphoma after prior skin-directed therapy.
- Valchlor is applied as a thin film once daily to affected skin areas.
- Apply Valchlor within 30 minutes of taking it out of the refrigerator, and return it to the refrigerator right after use.
- Apply Valchlor to completely dry skin, then let it dry 5 to 10 minutes before covering with clothing.
- Do not cover Valchlor-treated areas with occlusive dressings, and avoid fire, flame, and smoking until it dries.
Mechlorethamine on the U.S. market: products, makers and brands
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.
1 company lists 1 Mechlorethamine product record with the FDA, mostly as topical cream, ointment or gel; the earliest marketing or approval year on record is 1949. Brand names on the directory include Mustargen, Valchlor; the rest are generics.
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.
How widely Mechlorethamine is used (Medicaid data)
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 1,601 medications we measure, Mechlorethamine ranks #1,490 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. | NDA | View NDC → |
Showing 1 of 1 products — FDA National Drug Code Directory. See every product, package size and price: browse all 1 Mechlorethamine NDCs →
Mechlorethamine side effects reported to the 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.
Mechlorethamine FDA approval history
How Mechlorethamine went from FDA review to the pharmacy shelf — the key milestones in its regulatory journey.
Source: Drugs@FDA.
Mechlorethamine 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.
The FDA’s enforcement reports list no Mechlorethamine recalls since July 2021.
✅No Mechlorethamine recalls on record since July 2021Source: FDA enforcement (recall) reports, via openFDA; our copy was last updated Sep 24, 2026.
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
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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.
Mechlorethamine supply and 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.
Mechlorethamine brand names
Mechlorethamine is sold under 2 brand names in the FDA directory — Mustargen, Valchlor. A brand and its generic contain the same active ingredient; the brand name belongs to one company's product.
Who makes Mechlorethamine: manufacturers and labelers
One company lists Mechlorethamine products with the FDA. By number of product records, the largest are Helsinn Therapeutics (U.S.), Inc.. Labelers include manufacturers and repackagers; the product in your bottle depends on which one your pharmacy stocks.
Mechlorethamine drug class (RxNorm)
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.
Sources for this Mechlorethamine page
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 this page is built
HelloPharmacist combines public FDA and NLM records and does not author the underlying clinical facts. The plain-language sections are written with AI from the FDA-approved label text and reviewed by our pharmacy team before publication. Helsinn Therapeutics (U.S.), Inc. is the representative DailyMed label linked for verification and dates. This is general education, not medical advice: always talk to your doctor or pharmacist about your own medicines. How we build and review drug pages →