Diethylcarbamazine

Pronunciation: dye-eth-il-kar-BAM-a-zeen.

Generic name: diethylcarbamazine citrate (DEC)
Drug class: Antifilarial (piperazine derivative anthelmintic)
Form: Tablet (historic brand strengths: 50 mg; current WHO-prequalified Eisai product: 100 mg)
Route: Oral
Legal status: Prescription/programme-controlled -- not sold at retail pharmacies in the reference markets reviewed; obtained only through a specialist supply pathway (CDC Drug Service IND protocol in the US; WHO-donated mass drug administration in endemic countries)

Availability and supply rules vary by country

Trade names by country: United States · Canada

What diethylcarbamazine citrate (DEC) is and how it works

Diethylcarbamazine (DEC) is an antifilarial medicine that has been used since the late 1940s to treat and prevent infections caused by filarial parasitic worms. It kills the immature larval and, to a lesser extent, adult stages of the parasites that cause lymphatic filariasis and loiasis. (2) (8)

DEC is not a medicine you can buy at a pharmacy in most countries -- it is used only under direct medical/programme supervision after a confirmed diagnosis or a documented high risk of exposure, because of two genuinely serious risks: a real, potentially fatal risk of brain injury (encephalopathy) in people with very high Loa loa parasite loads in their blood, and an expected inflammatory reaction as the parasites die. Blood testing before treatment, and close medical supervision during it, are essential parts of how this medicine is used safely.

Mechanism of action: how diethylcarbamazine citrate (DEC) works

Diethylcarbamazine's precise mechanism is not fully established, but it is understood to immobilise and kill microfilariae (by altering their surface and making them more susceptible to the host immune system) and to have some activity against adult filarial worms. (2) (8) (10)

What diethylcarbamazine citrate (DEC) is used for

Lymphatic filariasis

Used to treat infection with the filarial worms Wuchereria bancrofti, Brugia malayi, or Brugia timori, which can damage the lymphatic system and, over time, cause severe limb or genital swelling (lymphoedema/elephantiasis) if untreated. (2)

Tropical pulmonary eosinophilia

Used to treat this lung condition, an unusual immune reaction to filarial infection causing cough, wheeze, and very high eosinophil (a type of white blood cell) counts. (2)

Loiasis, including prevention in high-risk travellers/residents

Used to treat infection with the Loa loa filarial worm (which can cause the characteristic migrating 'eye worm' and Calabar swellings), and also used preventively in people determined to be at increased ongoing risk of Loa loa infection, such as those living for extended periods in Central or West African forest regions. (2)

Before taking diethylcarbamazine citrate (DEC)

Do not take / not appropriate for

Do not take diethylcarbamazine if you have, or might have, onchocerciasis (river blindness) that has not been ruled out -- treating undiagnosed onchocerciasis with DEC can trigger a severe, vision-threatening inflammatory reaction. Screening for onchocerciasis is required first in anyone with relevant exposure history. (all countries/programmes) (2)
Do not take diethylcarbamazine without a pre-treatment quantitative blood smear if you have a relevant travel or residence history in Central or West Africa -- this is required to measure your Loa loa microfilarial load and assess encephalopathy risk before any dose is given. (all countries/programmes) (2)
Diethylcarbamazine is not recommended in pregnancy -- no adequate data exist on its safety or on how the dose should be adjusted in pregnant patients, and the risks are considered to outweigh the potential benefits outside of specialist-directed exceptions. (all countries/programmes) (10)

Tell your clinician about

Any travel or residence history in areas where Loa loa or onchocerciasis (river blindness) are found, so the correct pre-treatment blood testing can be arranged.
Any history of kidney problems, since severe Loa loa-related reactions can include kidney injury requiring close monitoring.
Whether you are pregnant, trying to become pregnant, or breastfeeding.
All other medicines and health conditions, especially any other current parasitic infection.

(2) (10)

How to take diethylcarbamazine citrate (DEC)

Diethylcarbamazine is only given after your specific filarial diagnosis (or documented high exposure risk) has been confirmed, and after any required pre-treatment blood testing (including quantitative Loa loa microfilarial counts where relevant) has been completed.
Take diethylcarbamazine exactly as directed by the clinician or programme supervising your treatment -- the dosing schedule, course length, and any pre-treatment steps depend on which condition is being treated and your individual risk factors.
Taking it with food may reduce stomach upset.

(2) (10)

Procedures and treatment changes

Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1) (2) (3) (4) (5) (6) (7) (8) (9) (10)

Missed dose

Contact the clinician or programme supervising your treatment for guidance if you miss a dose. Do not double up on a dose or otherwise change your schedule on your own -- both the dose and its timing are set individually based on your specific diagnosis and blood test results.

Overdose

Seek urgent medical attention immediately if you think too much diethylcarbamazine has been taken, or if severe vomiting, confusion, unusual drowsiness, seizures, or difficulty breathing occur -- an emergency medical team can assess and treat these symptoms. (10)

Side effects

Side effects and their urgency vary; report severe, persistent, or concerning symptoms.

Nausea and vomiting.

What to notice: Nausea and vomiting.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (10)

Dizziness and headache.

What to notice: Dizziness and headache.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (2) (10)

Fever and general muscle or joint aches.

What to notice: Fever and general muscle or joint aches.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (2) (10)

Visual disturbance.

What to notice: Visual disturbance.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (10)

Serious warnings

Signs of encephalopathy in people with a high Loa loa parasite load — life_threatening

Symptoms: New confusion, severe headache, drowsiness, unusual behaviour, difficulty walking or speaking, seizures, or loss of consciousness, occurring during or shortly after treatment.

Action: Seek emergency medical help immediately. This is a real, recognised, potentially fatal complication of diethylcarbamazine (and ivermectin) treatment in people with very high circulating Loa loa microfilarial levels (at or above 8,000 microfilariae per mL of blood) -- caused by the intense inflammatory response as large numbers of microfilariae die, not by direct drug toxicity. This is precisely why a pre-treatment quantitative blood smear is required in anyone with relevant exposure history, and why neither steroid pretreatment nor a slower dose increase reliably prevents this risk -- treatment decisions at high microfilarial loads are made by a tropical medicine specialist. (2)

Signs of kidney injury after treatment in high-risk patients — high_caution

Symptoms: A marked drop in urine output, swelling, or unusual tiredness following treatment in someone with a known high Loa loa load.

Action: Seek urgent medical assessment immediately -- kidney injury can accompany the same severe inflammatory reaction that causes encephalopathy at high Loa loa microfilarial loads. (2)

Mazzotti-type allergic/inflammatory reaction as microfilariae die — expected_but_can_be_severe

Symptoms: Intense itching, hives or rash, swollen lymph nodes, fever, joint pain, low blood pressure, and (if undiagnosed onchocerciasis is present) worsening skin and eye symptoms; these typically last around 3 to 7 days.

Action: Contact the clinician or programme supervising your treatment promptly, especially if eye symptoms, breathing difficulty, or low blood pressure develop -- seek emergency medical help immediately for any of those. This reaction happens because DEC kills microfilariae quickly, triggering an immune/inflammatory response; it is an expected, drug-class-typical effect rather than a true drug allergy, but it can be severe -- particularly vision-threatening -- when there is undiagnosed co-existing onchocerciasis, which is why that must be ruled out before treatment. (2) (10)

Signs of a severe allergic reaction (anaphylaxis) — emergency

Symptoms: Swelling of the face, lips, tongue, or throat; difficulty breathing; widespread hives.

Action: Seek emergency medical help immediately. (10)

Interactions

Diethylcarbamazine must not be given to someone with undiagnosed or confirmed onchocerciasis co-infection without specialist management, because of the risk of a severe ocular/skin Mazzotti-type reaction. (2)
Combined mass-treatment regimens that pair diethylcarbamazine with albendazole (and, in some national programmes, ivermectin) are used under structured public-health protocols; these combinations are managed entirely by the treating programme, not decided by the patient. (2)

Pregnancy, breastfeeding, kidney/liver function, age

Pregnancy

Not recommended -- no adequate safety or dosing data exist for diethylcarbamazine in pregnancy, and the risks are generally considered to outweigh the benefits outside specific specialist-directed exceptions. (1) (2) (3) (4) (5) (6) (7) (8) (9) (10)

Breastfeeding

Discuss with the treating clinician or programme -- specific breastfeeding safety data for diethylcarbamazine are limited in the sources reviewed for this dossier. (1) (2) (3) (4) (5) (6) (7) (8) (9) (10)

Children

Used from around 18 months of age for lymphatic filariasis under the same specialist/programme supervision and weight-based dosing principles as adults. (1) (2) (3) (4) (5) (6) (7) (8) (9) (10)

Elderly

No specific age-based dose adjustment is described in the sources reviewed; the same pre-treatment screening and monitoring principles apply. (1) (2) (3) (4) (5) (6) (7) (8) (9) (10)

Renal Impairment

Requires caution and close monitoring, particularly because severe Loa loa-related reactions can include kidney injury; dose and monitoring are individualised by the treating specialist. (1) (2) (3) (4) (5) (6) (7) (8) (9) (10)

Monitoring

Before starting

Confirmed filarial diagnosis (or documented high-risk exposure for loiasis prophylaxis)
Quantitative blood smear for Loa loa microfilarial density in anyone with relevant Central/West African exposure history
Screening to rule out co-existing onchocerciasis

During treatment

Close clinical observation for signs of encephalopathy (confusion, severe headache, seizures) in anyone with a high pre-treatment Loa loa load.
Monitoring for the expected Mazzotti-type inflammatory reaction (fever, rash, itching, joint pain) as microfilariae die.
Kidney function monitoring in patients with high Loa loa loads or any signs of a severe reaction.

(2)

Storage

Store tablets at room temperature, protected from moisture, out of reach of children, exactly as directed by the clinician or programme that supplied the medicine.

Professional information

Clinician-facing context only, sourced from CDC clinical guidance and WHO prequalification documentation; verify against current CDC/WHO/national-programme guidance before prescribing, since diethylcarbamazine is supplied through specialist/programme channels rather than a standard commercial label in the reference markets reviewed.

United States (CDC Drug Service, IND protocol)

Indication: Lymphatic filariasis / tropical pulmonary eosinophilia / loiasis (treatment and prophylaxis)

Dose summary: Lymphatic filariasis: 1-day or 12-day course, DEC 6 mg/kg/day (adults and children >=18 months). Tropical pulmonary eosinophilia: 14-21 day course at the same general dose principle. Loiasis: individualised, contingent on pre-treatment Loa loa microfilarial density.

Renal context: No standard renal dose-adjustment table found in the sources reviewed; caution and closer monitoring are used in the presence of Loa loa-related kidney injury risk. (2)

Global (WHO Global Programme to Eliminate Lymphatic Filariasis, national mass drug administration)

Indication: Lymphatic filariasis mass treatment/prevention

Dose summary: Administered under structured national programme protocols using WHO-prequalified diethylcarbamazine citrate 100 mg tablets (Eisai), sometimes co-administered with albendazole (or ivermectin, per programme-specific combination protocols) -- dosing is set at the programme level, not by the individual patient. (8) (9)

Mechanism of action

Overdose note

No specific antidote identified in the sources reviewed; manage with supportive care and close monitoring for encephalopathy-type reactions, particularly in anyone with a high Loa loa load. (2) (8) (10)

Frequently asked questions

Can I buy diethylcarbamazine at a pharmacy in the US, UK, Europe, Canada, Australia, or New Zealand?

No, not as a normal retail purchase in any of these 6 countries. In the United States it is supplied only by the CDC Drug Service under an investigational new drug protocol after a confirmed filarial diagnosis. Its former Canadian brand (Hetrazan) was cancelled from the market in 2000, and no current UK, EU, or Australian product listing was found. Globally, diethylcarbamazine reaches patients mainly through WHO-donated tablets used in national lymphatic-filariasis-elimination programmes in endemic countries. (1) (3) (4) (5) (6) (8)

Why is a blood test required before starting diethylcarbamazine?

If you have relevant travel or residence history in Central or West Africa, a quantitative blood smear is required to measure your Loa loa microfilarial load before any dose is given. This is because, at very high loads (8,000 or more microfilariae per mL of blood), diethylcarbamazine (like ivermectin) carries a real, potentially fatal risk of encephalopathy (brain injury) from the intense inflammatory response as large numbers of microfilariae die quickly. This risk is not reliably prevented by pretreatment with steroids or by increasing the dose slowly, so specialist input is needed at high microfilarial loads. (2)

Is the itching and fever after treatment a drug allergy?

Usually not a true allergy to diethylcarbamazine itself -- it is most often a Mazzotti-type reaction, the body's inflammatory response to microfilariae (parasite larvae) dying quickly after treatment. It typically causes itching, rash, fever, swollen lymph nodes, and joint pain lasting around 3 to 7 days. It can be more severe, and particularly threaten vision, if there is undiagnosed onchocerciasis (river blindness) present, which is why that infection is screened for before treatment. (2) (10)

What is the mechanism of action of diethylcarbamazine citrate (DEC)?

What is the generic name of Diethylcarbamazine?

The generic name is diethylcarbamazine citrate (DEC). (2) (4) (8)

What class of drug is diethylcarbamazine citrate (DEC)?

Diethylcarbamazine is classed as: Antifilarial (piperazine derivative anthelmintic). (2) (4) (8)

References

Diethylcarbamazine citrate -- DailyMed listing (bulk ingredient for animal drug compounding only; NDC 73309-183-01)U.S. National Library of Medicine / DailyMed · United States · accessed 2026-07-31 · source 1
Clinical Treatment of Lymphatic Filariasis -- CDC (Filarial Worms)U.S. Centers for Disease Control and Prevention (CDC), Division of Parasitic Diseases and Malaria / Drug Service · United States · accessed 2026-07-31 · source 2
CDC Infectious Diseases Laboratories -- Drug Service FormularyU.S. Centers for Disease Control and Prevention (CDC) Drug Service · United States · accessed 2026-07-31 · source 3
HETRAZAN (diethylcarbamazine citrate 50 mg tablet) -- DPD product record, DIN 00040819Health Canada Drug Product Database (DPD) · Canada · accessed 2026-07-31 · source 4
emc search for "diethylcarbamazine" -- no resultselectronic medicines compendium (emc), United Kingdom · United Kingdom · accessed 2026-07-31 · source 5
Search for diethylcarbamazine in the Australian Register of Therapeutic Goods (ARTG) -- no product entry foundTherapeutic Goods Administration (TGA), Australia · Australia · accessed 2026-07-31 · source 6
Medicines Amendment Regulations 2009 -- diethylcarbamazine listed as scheduled item 533New Zealand Legislation (Medicines Amendment Regulations 2009, SR 2009/212) · New Zealand · accessed 2026-07-31 · source 7
Eisai WHO prequalification and free-of-charge donation of diethylcarbamazine citrate tablets for lymphatic filariasis eliminationWorld Health Organization (WHO) / Eisai Co., Ltd. · Global (WHO Global Programme to Eliminate Lymphatic Filariasis, GPELF) · accessed 2026-07-31 · source 8
Diethylcarbamazine Citrate 100 mg Tablets (Eisai Co., Ltd) -- WHO Public Assessment Report, Part 4World Health Organization Prequalification Team · Global (WHO prequalification programme) · accessed 2026-07-31 · source 9
Diethylcarbamazine -- anthelmintic uses, warnings, side effects, dosage (aggregated clinical reference sources)Aggregated clinical-reference literature (MedicineNet, RxList, Medscape/Hetrazan monograph, DrugBank) · General clinical reference · accessed 2026-07-31 · source 10

Brand names by country

Single-ingredient diethylcarbamazine citrate (DEC) names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.

Priority countries

United States

Hetrazan (historic; discontinued) (1)no longer marketed no current fda human label · Historic -- Wyeth-Ayerst / Lederle (no current holder; not commercially available)

Canada

Hetrazan (historic; cancelled 2000) (4)din cancelled post market 2000-08-02 · 50 mg · Lederle Cyanamid Canada Inc. (historic; DIN 00040819)

View brands in additional countries.