An older HIV medicine (an NRTI), now rarely used
Didanosine
An older HIV medicine (a nucleoside reverse transcriptase inhibitor) once used in combination therapy but now rarely chosen because of its side effects.
What is Didanosine?
Didanosine is an older HIV medicine, a type called a nucleoside reverse transcriptase inhibitor (NRTI). It was used as part of combination therapy, always with other HIV medicines and never on its own. It is now rarely used because it can cause serious inflammation of the pancreas (pancreatitis), nerve damage in the hands and feet (peripheral neuropathy), and a serious build-up of acid in the blood (lactic acidosis). It is taken on an empty stomach. Newer, safer NRTIs are preferred, so didanosine is mostly of historical importance in the UK.
Education and reference only. This is a plain-language guide to Didanosine — 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
Didanosine is an antiretroviral medicine used to treat HIV. It belongs to a group called nucleoside reverse transcriptase inhibitors (NRTIs). Like all HIV medicines, it was only ever used as part of combination therapy, alongside other antiretrovirals and never on its own, because a single HIV medicine used alone lets the virus become resistant. It is taken by mouth on an empty stomach, as food reduces how well it is absorbed. Today it is rarely used because of its side effects, and has largely been replaced by safer, better-tolerated options.
How it works
HIV uses an enzyme called reverse transcriptase to copy itself and multiply. Didanosine is taken into this process and blocks the enzyme, so the virus cannot reproduce properly and the amount of virus in the body is kept down. Because HIV can quickly become resistant to any single medicine, didanosine works as part of a combination of antiretrovirals attacking the virus in different ways. Keeping the virus suppressed protects the immune system, but didanosine's tendency to inflame the pancreas, damage nerves and disturb the body's energy chemistry is why it is now seldom chosen.
Company & origin
Originated / developed by: Generic / specialist manufacturer.
An older HIV medicine used in the UK as part of combination therapy in the past; now rarely used because of its side effects, with newer, safer options preferred.
Practical use
How to take Didanosine
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Take it by mouth on an empty stomach, away from food, exactly as prescribed.
- Always take it together with the other HIV medicines in your combination, never on its own.
- Take it consistently and on time, as missing doses can let the virus become resistant.
- Seek urgent medical help for severe tummy pain, especially spreading to the back with sickness, which can signal pancreatitis.
- Report numbness, tingling or pain in your hands or feet, and keep all your specialist HIV appointments.
Weighing it up
Advantages & disadvantages of Didanosine
Advantages
- An effective HIV medicine in its time, helping suppress the virus as part of combination therapy.
- Taken by mouth.
- Played an important historical role in early HIV treatment.
Disadvantages
- Can cause serious inflammation of the pancreas (pancreatitis).
- Can cause nerve damage in the hands and feet and a rare but serious build-up of acid in the blood.
- Must be taken on an empty stomach, and is now rarely used as safer NRTIs are preferred.
Practical use
Good to know
The key things to know about didanosine are the reasons it is now rarely used. It can cause inflammation of the pancreas (pancreatitis), which can be severe; warning signs are severe tummy pain spreading to the back, with nausea and vomiting, and need urgent medical attention. It can damage the nerves in the hands and feet, causing pain, numbness or tingling that can be lasting. It can also cause a rare but dangerous build-up of lactic acid in the blood (lactic acidosis) with liver problems. It needs to be taken on an empty stomach, away from food, which can be inconvenient. Because of these risks, safer newer NRTIs are preferred. As with all HIV treatment, it must be taken consistently and always as part of a combination, under specialist care.
Who should not take it / use with caution
- People who have had a serious allergic reaction to didanosine should not take it.
- It is avoided or used with great caution in people with a history of pancreatitis, nerve damage, liver problems or risk factors for lactic acidosis.
- It is not used on its own, and is generally avoided in favour of safer HIV medicines under specialist care.
Monitoring
- Regular blood tests including the amount of virus (viral load), immune cells (CD4 count) and liver function.
- Watching for signs of pancreatitis, nerve damage and lactic acidosis.
- Reviewing the overall HIV combination and considering safer alternatives.
Side effects
- Inflammation of the pancreas (pancreatitis), with severe tummy pain, nausea and vomiting, which needs urgent care.
- Numbness, tingling or pain in the hands and feet from nerve damage (peripheral neuropathy).
- Rarely but seriously, a build-up of lactic acid in the blood (lactic acidosis) with liver problems.
- Nausea, diarrhoea or headache in some people.
Key interactions
- Combining it with stavudine adds to the risk of nerve and pancreas problems and is avoided.
- It should not be combined with certain other medicines that increase its levels or add to pancreas risk, such as some used for HIV or related infections.
- Tell your specialist about all your medicines, as the HIV combination is chosen carefully and didanosine must be spaced from some medicines and food.
Available as: Gastro-resistant capsules taken by mouth on an empty stomach.
Answers
Didanosine: frequently asked questions
What is didanosine used for?
It is an older HIV medicine used as part of combination therapy to help keep the virus suppressed; it is always used with other HIV medicines, never alone.
Why must I take it on an empty stomach?
Food reduces how well didanosine is absorbed, so it is taken away from food for the best effect.
Why is it now rarely used?
It can cause pancreatitis, nerve damage and a rare but serious build-up of acid in the blood, so safer newer medicines are preferred.
What are the warning signs of pancreatitis?
Severe tummy pain, especially spreading to the back with nausea and vomiting, can signal pancreatitis and needs urgent medical attention.
Can it be taken on its own?
No. Like all HIV medicines it must be part of a combination, because using one HIV medicine alone lets the virus become resistant.
The wider class
About Antiretroviral (NRTI) for HIV
Didanosine belongs to the antiretroviral (nrti) for hiv class. For how the class as a whole works, its shared safety principles and monitoring, see the full guide.
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Authoritative sources
- BNF
- NICE CKS
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