Diethylcarbamazine
Anthelmintics
Anthelmintics
Oral antifilarial that clears microfilariae and harms adult worms in lymphatic filariasis and loiasis; dangerous if onchocerciasis is present.
Also called: DEC, diethylcarbamazine citrate
Quick facts
- Group
- Anthelmintics
- Target
- Filarial microfilariae and adult worms (mechanism not established)
- Used for
- Lymphatic filariasis · Loiasis
- Key effects
- Dizziness · Fever and muscle or joint pain
- Monitor
- Fever · Eye symptoms or confusion
- ATC
- P02CB02
No doses: the clinician sets them by the current guideline.
Mechanism of action
Diethylcarbamazine is a piperazine derivative whose exact mechanism is unknown. Microfilariae of Wuchereria bancrofti, Brugia malayi and Loa loa vanish quickly from the blood after a dose, and the drug also damages some adult worms. Most adverse effects come from the host's inflammatory response to the dying parasites, not from the drug itself.
- Microfilariae in the blood become vulnerable (exact mechanism unknown)
- The immune system clears them quickly from the blood
- Some adult worms in lymphatics are also killed
- Dying parasites trigger the inflammatory side effects
Indications
- Lymphatic filariasis (individual treatment, and with albendazole, or ivermectin and albendazole, in mass drug administration where onchocerciasis is absent) Lymphatic filariasis →
- Loiasis, with specialist care when the microfilarial load is high
- Tropical pulmonary eosinophilia (longer course)
Adverse effects
Common
- Dizziness, nausea and headache
- Fever and muscle or joint pain, more with heavy microfilarial loads
- Painful lymph nodes or lymphatic swelling as adult worms die
Contraindications
- Onchocerciasis, or possible co-infection, because of severe skin and eye reactions
- High Loa loa microfilarial load, except under specialist care
Key interactions
- Urine-alkalinising drugs
- Alkaline urine slows elimination and raises levels, increasing both effect and toxicity.
- Albendazole and ivermectin
- Combined in mass treatment for lymphatic filariasis where onchocerciasis and loiasis are absent.
What is monitored
- Fever, headache and joint pain in the first days (reactions to dying parasites)
- Eye symptoms or confusion, which need urgent assessment
- Microfilarial count before and after treatment
Administration and safety
- Oral
- Onchocerciasis is ruled out first in anyone exposed in an endemic area
- Loa loa is screened for before treatment in people from Central and West Africa
Pregnancy and breastfeeding
Available data suggest it is safe in pregnancy; it is still given only after the infection and possible co-infections have been assessed.
Nursing care
- Ask about travel or residence in areas with onchocerciasis or loiasis
- Warn that fever and aches in the first days usually mean worms are dying, and report eye pain or confusion
- Explain that lymphoedema and hydrocele do not improve with DEC and need limb care or surgery
- Teach mosquito-bite prevention
Pharmacokinetics
- Absorption
- Rapidly absorbed by mouth.
- Elimination
- Mainly by the kidneys; alkaline urine slows elimination and raises levels, so kidney function and urine pH matter.
Test yourself
Think of the answer, then tap the question to see it.
Why must onchocerciasis be ruled out before giving diethylcarbamazine?
Killing Onchocerca microfilariae in skin and eyes causes a severe reaction (Mazzotti) and can damage the eyes.
What causes most of DEC's adverse effects?
The host's inflammatory response to dying microfilariae and adult worms, more intense with heavy infection.
Which complication is feared when DEC is given to someone with a high Loa loa load?
Encephalopathy, which can be fatal, along with retinal haemorrhage and kidney failure.
Does DEC reverse established lymphoedema or hydrocele?
No. Most affected people no longer have active infection; limb care helps lymphoedema and hydrocele needs surgery.
Connections
← Back to the class: Anthelmintics
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Clinical Treatment of Lymphatic Filariasis (Centers for Disease Control and Prevention (CDC), 2026); Lymphatic filariasis (World Health Organization (WHO), 2026); eEML - Electronic Essential Medicines List (World Health Organization (WHO), 2026).
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Representative model, for educational purposes only.