A medicine for filarial worm infections such as lymphatic filariasis
Diethylcarbamazine
A specialist medicine used to treat filarial worm infections, such as lymphatic filariasis and loiasis.
What is Diethylcarbamazine?
Diethylcarbamazine is a specialist medicine used to treat filarial worm infections, a group of tropical diseases caused by thread-like worms spread by insect bites, including lymphatic filariasis (which can cause severe limb swelling) and loiasis (the African eye worm). It is taken by mouth under specialist tropical-medicine care. A crucial safety point is that, as the worms die, the body can react strongly with fever, itching, swelling and aches (a Mazzotti-type reaction), and in people with a heavy loiasis or onchocerciasis (river blindness) infection this reaction can be serious, so treatment is carefully planned and supervised.
Education and reference only. This is a plain-language guide to Diethylcarbamazine — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Diethylcarbamazine is a medicine used to treat infections caused by filarial worms, a group of thread-like parasites spread by the bites of insects such as mosquitoes and flies. These infections include lymphatic filariasis, which can cause long-term swelling of the limbs, and loiasis, caused by the African eye worm. It is taken by mouth and is used under the care of a specialist in tropical or infectious diseases, because both the infections and the treatment need careful handling. It is not a routine medicine in the UK but is used for people who have these specific tropical infections.
How it works
Diethylcarbamazine acts against the tiny early-stage worms (microfilariae) circulating in the blood and also affects the adult worms, helping the immune system clear the infection. As large numbers of worms are killed, the body's immune system reacts to the dying parasites, which is what causes the fever, itching, rash, swelling and aches that often follow treatment. This reaction tends to be stronger when there are many worms present. Because the strength of this reaction depends on how heavy the infection is, the specialist plans treatment carefully and watches closely, especially in heavy infections.
Company & origin
Originated / developed by: Specialist manufacturers.
A specialist tropical-medicine treatment used for filarial worm infections such as lymphatic filariasis and loiasis.
Practical use
How to take Diethylcarbamazine
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Take it by mouth exactly as the specialist tropical-medicine team prescribes.
- Expect that, as the worms die, you may get fever, itching, rash, swelling or aches; tell the team if these are severe.
- Attend all appointments, as treatment may be started gently and built up under close supervision.
- Report any severe reaction, eye symptoms, confusion or feeling very unwell straight away, especially if you have loiasis or river blindness.
- Tell the team your full travel history and about any other infections, as these affect how treatment is planned.
Weighing it up
Advantages & disadvantages of Diethylcarbamazine
Advantages
- An effective specialist treatment for filarial worm infections such as lymphatic filariasis and loiasis.
- Taken by mouth under specialist supervision.
- A long-established medicine with extensive experience in tropical medicine.
Disadvantages
- As the worms die, it commonly causes fever, itching, swelling and aches (a Mazzotti-type reaction).
- In heavy loiasis or river-blindness infection, the reaction can be serious, including effects on the brain or eyes.
- Needs careful specialist assessment and supervision before and during treatment.
Practical use
Good to know
The single most important thing to understand about diethylcarbamazine is the reaction that happens as the worms die. As the parasites are killed, the immune system reacts and can cause fever, itching, rash, swelling, headache and aches (a Mazzotti-type reaction), which is a sign the medicine is working but can be uncomfortable. Crucially, in people who have a very heavy loiasis infection, or who also have onchocerciasis (river blindness), this reaction can be severe and even dangerous, including effects on the brain or eyes, so the specialist must assess the infection carefully before and during treatment, sometimes lowering the starting amount or treating other infections first. It is taken by mouth under specialist tropical-medicine supervision, and you should report any severe reaction, eye symptoms or feeling very unwell straight away. Tell the team about your full travel and infection history.
Who should not take it / use with caution
- People who have had a serious allergic reaction to diethylcarbamazine should not take it.
- It is used with great caution, or avoided, in people with a heavy loiasis infection or onchocerciasis (river blindness) because of the risk of a severe reaction.
- It is used carefully in pregnancy and in people with significant heart, kidney or other illness, under specialist guidance.
Monitoring
- Assessing how heavy the infection is before treatment, especially for loiasis and river blindness.
- Watching closely for the reaction that follows as the worms die.
- Reviewing the response to treatment and any eye or nervous-system symptoms.
Side effects
- Fever, headache, itching, rash, swelling and aches as the worms die (a Mazzotti-type reaction).
- Feeling sick, being sick or dizziness.
- Tiredness or general feeling of being unwell.
- Rarely, severe reactions, including effects on the eyes or brain, particularly in heavy loiasis or river blindness, which need urgent care.
Key interactions
- The specialist considers other medicines, especially other treatments for worm infections, when planning treatment.
- Medicines that affect the immune reaction may be used alongside it to manage the response to dying worms.
- Tell the team about every medicine you take, as well as your full infection history.
Available as: Tablets taken by mouth.
Answers
Diethylcarbamazine: frequently asked questions
What is diethylcarbamazine used for?
It is a specialist medicine used to treat filarial worm infections, such as lymphatic filariasis and loiasis (the African eye worm), under tropical-medicine care.
Why do I feel unwell after taking it?
As the worms die, the immune system reacts, often causing fever, itching, swelling and aches (a Mazzotti-type reaction); it is a sign the medicine is working but should be reported if severe.
Why does loiasis or river blindness matter?
In people with a heavy loiasis infection or river blindness, the reaction to dying worms can be severe and dangerous, so the specialist must assess and supervise treatment carefully.
How is it taken?
It is taken by mouth, often started gently and built up, under the supervision of a specialist in tropical or infectious diseases.
What should I report straight away?
Report any severe reaction, eye symptoms, confusion or feeling very unwell, especially if you have loiasis or river blindness.
Authoritative sources
- BNF
- NICE CKS
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