Fluorouracil (Efudix): Uses, Side Effects and Shortage Information

MedWatch safety note: Fluorouracil is a prescription-only medicine (POM). This article is for patient information only. It does not replace advice from your GP, dermatologist, pharmacist, or cancer specialist. Do not start, stop, or change your treatment without speaking to a clinician.

Current UK Shortage Status

The Department of Health and Social Care (DHSC) issued Medicine Supply Notification MSN/2024/109 (updated 3 February 2025) for fluorouracil (Efudix®) 5% cream, imiquimod creams, and related topical products. The notification states that fluorouracil 5% cream is in limited supply and that unlicensed supplies may be sourced through specialist importers, with lead times that vary (CPE).

MedWatch continues to record this as an active supply issue as of 13 May 2026. The original notification did not specify a confirmed resupply date.

What this means for patients:

• Local pharmacy availability varies. Not all pharmacies will have Efudix in stock.
• Your pharmacy may be able to obtain an unlicensed import via a specialist importer such as Alium Medical, Chemys, Durbin, Genetech Pharmaceuticals, Mawdsleys, or Target Healthcare, subject to prescriber agreement and pharmacy capacity.
• Your prescriber may also discuss alternative treatments, such as imiquimod cream, photodynamic therapy (PDT), cryotherapy, curettage and cautery, or surgical excision.

Where to check live status: The NHS Specialist Pharmacy Service (SPS) Medicines Supply Tool provides up-to-date supply information for NHS staff. Patients should speak to their pharmacist or GP for the latest local availability.

Plain-English Summary

Fluorouracil — also known as 5-FU or 5-fluorouracil — is a medicine that interferes with the growth of abnormal cells. In the UK it is used in two ways:

1. As a cream (brand name Efudix®) applied directly to the skin to treat early skin cancers and pre-cancerous patches.
2. As an injection or infusion in hospital to treat advanced cancers such as bowel (colorectal) and breast cancer.

This article focuses mainly on the cream, because that is the form affected by the current UK supply issue. If you are receiving fluorouracil as chemotherapy, your oncology team will provide detailed counselling and monitoring.

What It Is Used For

Topical cream (Efudix 5%)

The 5% cream is licensed for the topical treatment of superficial pre-malignant and malignant skin lesions, including (eMC SmPC):

• Actinic (solar) keratosis — sun-damage related rough patches
• Senile (age-related) keratosis
• Keratoacanthoma
• Bowen's disease (squamous cell carcinoma in situ)
• Superficial basal cell carcinoma

It is not usually effective for deep, penetrating, or nodular basal cell carcinomas or invasive squamous cell carcinomas. In those cases it should only be used if no other treatment is possible, and only as palliative therapy (eMC SmPC).

The NHS lists 5-fluorouracil cream as one of the treatments for Bowen's disease, alongside cryotherapy, imiquimod, photodynamic therapy, curettage and cautery, and surgery (NHS).

Injection/infusion

Fluorouracil injection is used in hospital, alone or with other chemotherapy, for the palliative management of certain cancers — particularly cancer of the colon and breast (eMC SmPC 50 mg/ml).

How It Works

Fluorouracil belongs to a group of medicines called pyrimidine analogues (ATC code L01BC02). It is a cytostatic medicine, meaning it interferes with cell growth and division.

When applied to the skin as a cream, it affects abnormal (pre-cancerous and cancerous) skin cells more than normal skin cells. The typical treatment response follows this pattern: redness (erythema) → blistering (vesiculation) → skin breakdown (erosion/ulceration) → tissue shedding (necrosis) → healing with new skin growth (epithelialisation) (eMC SmPC).

At a molecular level, fluorouracil blocks thymidylate synthase, an enzyme cells need to make and repair DNA. Without DNA production, abnormal cells cannot multiply.

Forms and Strengths

The cream is supplied in 20 g and 40 g aluminium tubes (eMC SmPC).

Brand and Generic Names

• Generic: fluorouracil (also 5-fluorouracil, 5-FU)
• UK brand name (cream): Efudix®
• Other brand names (injection): various hospital-specialist brands

Invention and Approval History

Fluorouracil was developed from the observation that tumour cells absorb the natural body chemical uracil at high rates. Researchers created a fluorinated analogue that tumour cells take up but cannot use properly, disrupting DNA production. It has been used in cancer medicine since the 1960s and remains on the World Health Organization's List of Essential Medicines.

In the UK, Efudix 5% cream holds Marketing Authorisation PL 46302/0128, with first authorisation on 22 July 2008 (eMC SmPC).

How Medicines of This Type Are Made

Fluorouracil is produced by chemical synthesis. It is a fluorinated analogue of uracil, a natural building block of RNA. Chemists introduce a fluorine atom at a specific position on a pyrimidine ring to create a molecule that mimics a normal cell nutrient but disrupts DNA production once inside the cell. Detailed manufacturing instructions are not publicly disclosed for safety and regulatory reasons.

UK Suppliers and Marketing Authorisation Holders

Efudix 5% cream:

• Marketing Authorisation Holder: Viatris Products Limited, Potters Bar, Hertfordshire, UK (eMC SmPC; eMC PIL)

During the current shortage, the following specialist importers have been listed as able to source unlicensed supplies of fluorouracil 5% cream (CPE):

• Alium Medical
• Chemys
• Durbin
• Genetech Pharmaceuticals
• Mawdsleys
• Target Healthcare

*Note: Unlicensed imports may require special prescribing arrangements. Your pharmacist will advise on what is needed.*

Systemic injection products:

• Various manufacturers supply hospital-use injections. One UK supplier is medac GmbH (trading as medac Pharma LLP), which has previously issued precautionary recalls for certain batches.

Common Side Effects

Topical cream (expected local reactions)

When used correctly, fluorouracil cream causes a deliberate inflammatory reaction on treated skin. This is part of how the medicine works. The normal pattern includes (eMC SmPC):

• Redness (erythema) — often intense
• Blistering
• Skin erosion or ulceration
• Pain, burning, or stinging
• Crusting, weeping, or scabbing
• Itching
• Increased sensitivity to sunlight

These effects typically appear in the second week of treatment. Healing may continue for one or two months after treatment stops. Lesions on the face usually respond faster than those on the trunk, hands, or lower limbs (eMC SmPC).

Severe discomfort can sometimes be eased with a topical steroid cream — ask your prescriber or pharmacist before using one.

Systemic side effects (injection/infusion)

These are relevant to hospital chemotherapy rather than standard topical use, but are included for completeness:

• Nausea, vomiting, diarrhoea
• Mouth ulcers (stomatitis)
• Hair loss (alopecia)
• Increased risk of infection (due to low white blood cells)
• Bruising or bleeding (due to low platelets)
• Tiredness and weakness
• Sore, red, peeling skin on palms and soles (hand-foot syndrome)
• Changes to heart rhythm

(eMC SmPC 50 mg/ml; Cancer Research UK)

Serious Side Effects and Urgent Help

Call 999 or go to A&E immediately if you have:

• Signs of a severe allergic reaction: swelling of the face, lips, tongue, or throat; difficulty breathing; severe rash or itching
• Chest pain, shortness of breath, or palpitations
• Signs of severe infection: fever, chills, shaking, feeling very unwell
• Severe or persistent diarrhoea (especially if receiving systemic treatment)

Contact your GP, dermatologist, or NHS 111 urgently if:

• The treated skin becomes severely ulcerated or blistered and you cannot manage the pain
• You develop a widespread rash away from the treated area
• You feel generally unwell with fever, nausea, vomiting, or mouth sores during topical treatment
• You accidentally swallow the cream (seek immediate medical advice)
• You experience severe skin inflammation that is spreading beyond the treated area

(eMC SmPC; eMC SmPC 50 mg/ml)

Interactions and Cautions

Medicines you must not use with fluorouracil

Brivudine, sorivudine, and similar antiviral medicines are potent inhibitors of an enzyme called dihydropyrimidine dehydrogenase (DPD), which breaks down fluorouracil. Using them together can cause life-threatening toxicity. This combination is contraindicated. An interval of at least four weeks must pass between treatment with these antivirals and using fluorouracil (eMC SmPC).

Phenytoin (an anti-seizure medicine) levels may rise when used with systemic fluorouracil; regular blood tests are recommended (eMC SmPC 50 mg/ml).

Leucovorin (folinic acid) can increase the anti-cancer effect of systemic fluorouracil but also increases the risk of stomach and blood side effects (eMC SmPC 50 mg/ml).

Vaccines

Live vaccines (such as MMR, BCG, yellow fever) should be avoided during systemic fluorouracil treatment and for some time afterwards because the immune system may be suppressed. Inactivated vaccines may be given but may not work as well. Ask your clinician about timing if you are receiving systemic treatment (Cancer Research UK).

General cautions

• Fire hazard: Fabric (clothing, bedding, dressings) that has been in contact with fluorouracil cream burns more easily. Do not smoke or go near naked flames. Washing may reduce build-up but will not fully remove it (eMC SmPC).
• Sunlight: Avoid UV exposure, including natural sunlight and tanning salons, during treatment (eMC SmPC).
• DPD deficiency: Some people have low or absent activity of the DPD enzyme, which means their body cannot break down fluorouracil properly. This increases the risk of severe toxicity. If you have ever had unusually severe reactions to fluorouracil or similar drugs, tell your doctor before starting treatment. DPD activity testing may be considered, particularly before systemic use (eMC SmPC; eMC SmPC 50 mg/ml).
• Application-site safety: Keep the cream away from eyes, mouth, mucous membranes, and broken skin unless specifically directed by your prescriber. Wash hands thoroughly after applying, unless treating the hands themselves (eMC PIL).
• Children and pets: Store all medicines out of reach of children and pets. Do not let others use your prescription.

Pregnancy, Breastfeeding, Driving, Alcohol, Kidney/Liver

Pregnancy

Fluorouracil must not be used during pregnancy. Animal studies have shown that fluorouracil causes birth defects (teratogenic), including defects of the nervous system, palate, skeleton, and limbs. It crosses the placenta. Because of the animal data and the medicine's mechanism, it is contraindicated in pregnancy (eMC SmPC).

Contraception

• Women of childbearing potential: Use effective contraception during treatment and for 6 months after the last dose.
• Men: Use effective contraception and do not father a child during treatment and for 3 months after the last dose (eMC SmPC).

Breastfeeding

Do not breastfeed while using fluorouracil. No data are available on excretion into breast milk, but animal studies show teratogenicity, and a risk to the nursing infant cannot be excluded. If use during breastfeeding is absolutely necessary, breastfeeding must be discontinued (eMC SmPC).

Driving and machinery

Topical fluorouracil cream is unlikely to affect your ability to drive or use machines when used as directed (eMC SmPC). Systemic treatment may cause fatigue or other effects that could impair driving — follow your oncology team's advice.

Alcohol

The UK product information for topical fluorouracil does not list specific alcohol warnings. If you are receiving systemic chemotherapy, your oncology team may advise limiting alcohol because of effects on the liver and immune system.

Kidney and liver

For systemic fluorouracil, the liver helps clear the medicine from the body. Dose reduction may be needed in patients with impaired liver or kidney function — your oncology team will manage this (eMC SmPC 50 mg/ml). For topical use on intact skin, significant body-wide absorption is unlikely, so specific kidney or liver dose adjustments are not described in the cream product information.

Missed Dose and Stopping Suddenly

Missed dose: The UK product information reviewed for fluorouracil cream did not include specific missed-dose instructions. As a general principle for topical medicines, if you forget an application, apply it when you remember unless it is close to the time of your next scheduled application. Do not apply extra cream to make up for a missed dose. If you are unsure, ask your pharmacist or prescriber for advice.

Stopping treatment: Your prescriber will tell you how long to continue using the cream. Some inflammation of the treated skin is expected and is part of the treatment effect. However, seek urgent medical advice if you develop severe ulceration, widespread blistering, fever, or feel generally unwell (eMC SmPC).

For systemic chemotherapy, stopping or changing treatment must be managed by your oncology team.

Monitoring Requirements

Topical cream

• Routine blood monitoring is not usually required for standard topical use on small areas.
• The SmPC recommends treating no more than 500 cm² at one time (roughly 23 × 23 cm). If you are treating a large area, or if you have symptoms suggesting the medicine is being absorbed into your body, tell your clinician promptly.
• You should have follow-up appointments with your dermatologist or GP to check that the lesion has healed properly (NHS Bowen's disease).

Systemic injection/infusion

• Blood tests before and during each treatment cycle to check white blood cells, platelets, liver function, and kidney function.
• DPD deficiency assessment may be considered before starting treatment.
• Heart monitoring (ECG) if you have a history of heart disease.
• Daily monitoring of blood counts during initial inpatient treatment (eMC SmPC 50 mg/ml; Cancer Research UK).

What to Ask a Pharmacist or GP During Supply Issues

If your pharmacy cannot obtain Efudix cream, consider asking:

1. "Can you source an unlicensed import of fluorouracil 5% cream?" Specialist importers may be able to supply it, though this may require additional paperwork and take longer.
2. "What alternative treatments are suitable for my skin condition?" Depending on your diagnosis, alternatives may include imiquimod cream, photodynamic therapy, cryotherapy, curettage and cautery, or surgical excision.
3. "Should I continue using a partially used tube past its expiry?" Once opened, Efudix cream should be used within 90 days (eMC SmPC). Do not use expired cream.
4. "Is my repeat prescription still valid, or do I need a new review?" Skin conditions treated with fluorouracil require diagnosis and monitoring by a clinician; do not attempt to self-treat with old prescriptions or online purchases.

Related Medicines a Clinician May Discuss

Depending on your condition and the supply situation, your clinician may discuss:

(NHS Bowen's disease; CPE shortage page)

Official Sources and Correction Route

• Electronic Medicines Compendium (eMC): Search fluorouracil for all UK PILs and SmPCs.
• NHS: Bowen's disease information (includes 5-fluorouracil as a treatment option).
• Cancer Research UK: Fluorouracil drug information.
• MHRA Yellow Card: Report suspected side effects.
• DHSC/CPE Shortage Notifications: CPE shortage page.
• SPS Medicines Supply Tool: sps.nhs.uk (NHS staff only).

Found an error in this article? MedWatch articles are reviewed regularly. If you spot a factual error or outdated shortage status, please contact us or speak to your pharmacist or GP for the most current official guidance.

Frequently Asked Questions

1. Why does my skin look worse after starting fluorouracil cream?

This is usually expected. Fluorouracil works by causing a controlled inflammatory reaction. Redness, blistering, crusting, and soreness are normal — especially in the second week — and show the medicine is affecting abnormal cells. Healing typically continues for one to two months after you stop applying it. If pain is severe, contact your prescriber; a topical steroid may help (eMC SmPC).

2. Can I go in the sun while using Efudix?

No — avoid UV exposure as much as possible. This includes natural sunlight and tanning salons. Sun exposure can worsen the skin reaction and increase inflammation. Follow your prescriber's advice about sun protection during treatment (eMC SmPC).

3. Is Efudix cream available in the UK?

MedWatch currently records an active supply issue for fluorouracil 5% cream based on DHSC Medicine Supply Notification MSN/2024/109. Local pharmacy availability varies. Some pharmacies may be able to source unlicensed imports, or your prescriber may discuss alternative treatments. Speak to your pharmacist or GP for the latest local availability (CPE).

4. Can I use fluorouracil cream if I am pregnant or trying to conceive?

No. Fluorouracil is contraindicated in pregnancy because animal studies show it causes birth defects. Women should use effective contraception during treatment and for 6 months afterwards. Men should use contraception and avoid fathering a child during treatment and for 3 months afterwards. Do not breastfeed while using this medicine (eMC SmPC).

5. What should I do if I accidentally swallow some of the cream?

Seek medical advice immediately. Ingestion of fluorouracil can cause nausea, vomiting, diarrhoea, mouth ulcers, and dangerous changes in blood cell counts. Contact NHS 111 or your GP urgently, or go to A&E if you feel unwell (eMC SmPC).

6. I have been told I have a DPD deficiency — can I still use the cream?

Tell your doctor before starting treatment. DPD deficiency mainly affects systemic (injection) fluorouracil and can cause life-threatening toxicity. With topical cream, significant body-wide absorption is unlikely through intact skin, but it increases if skin is ulcerated or covered with an occlusive dressing. Your clinician will assess whether the cream is safe for you or whether an alternative treatment is preferable (eMC SmPC; eMC SmPC 50 mg/ml).