A salicylate-related NSAID painkiller
Diflunisal
An anti-inflammatory painkiller, related to aspirin, used for pain and inflammation such as in arthritis.
What is Diflunisal?
Diflunisal is a non-steroidal anti-inflammatory drug (NSAID) that is related to aspirin (a salicylate). It is used to relieve pain and inflammation, including in conditions such as osteoarthritis. It works by reducing the chemicals that cause pain and swelling. Like other NSAIDs, it can irritate the stomach and cause ulcers or bleeding, and it carries kidney and cardiovascular (heart and circulation) risks. Because it is related to aspirin, it should not be used by people who are allergic to aspirin or other NSAIDs.
Education and reference only. This is a plain-language guide to Diflunisal — 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
Diflunisal is a painkiller from the non-steroidal anti-inflammatory drug (NSAID) family, and it is chemically related to aspirin, which is a salicylate. It is used to relieve pain and to reduce inflammation, for example in conditions such as osteoarthritis and rheumatoid arthritis, and for other types of pain. It is taken by mouth. Like other NSAIDs, it eases pain and swelling but needs to be used carefully because of its effects on the stomach, kidneys and circulation.
How it works
Diflunisal works by blocking enzymes called COX enzymes, which the body uses to make prostaglandins — chemicals that cause pain, swelling and inflammation. By reducing these chemicals, it lessens pain and inflammation. The same prostaglandins also help protect the stomach lining and support blood flow to the kidneys, which is why blocking them can lead to stomach irritation and ulcers and can affect the kidneys. This is the trade-off common to all NSAIDs, and it is why the lowest effective amount for the shortest time is preferred.
Company & origin
Originated / developed by: Generic manufacturers.
An anti-inflammatory painkiller related to aspirin, used for pain and inflammation.
What it treats
Conditions Diflunisal is used for
Practical use
How to take Diflunisal
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Take it with or after food to reduce the chance of stomach upset.
- Use the lowest amount that controls your symptoms for the shortest time needed.
- Do not take it if you are allergic to aspirin or other NSAIDs, including if they cause wheezing or a rash.
- Report black stools, vomiting blood or severe stomach pain urgently, as these can signal bleeding.
- Tell your prescriber about other medicines, as it interacts with several, including some blood pressure and blood-thinning medicines.
Weighing it up
Advantages & disadvantages of Diflunisal
Advantages
- Effectively relieves pain and reduces inflammation.
- A useful option for ongoing painful, inflammatory conditions such as arthritis.
- Taken by mouth and long-acting, so it does not need to be taken as often as some painkillers.
Disadvantages
- Can irritate the stomach and cause ulcers or bleeding.
- Carries kidney risks and a small increased risk of heart and circulation problems.
- Cannot be used by people allergic to aspirin or other NSAIDs.
Practical use
Good to know
The main things to know about diflunisal are the usual NSAID risks. It can irritate the stomach and cause ulcers or bleeding, so it is taken with or after food, and any black stools, vomiting blood or persistent stomach pain should be reported urgently. It can affect the kidneys, particularly in older people, those who are dehydrated, or those with existing kidney problems, and it carries a small increased risk of heart and circulation problems such as heart attack and stroke, especially with higher amounts or long-term use. Because it is related to aspirin, anyone who has had an allergic reaction to aspirin or another NSAID — including wheezing or a rash — should not take it. It can also interact with several common medicines, so it is important to share a full medicines list.
Who should not take it / use with caution
- People who are allergic to aspirin or other NSAIDs, including those who get wheezing or a rash from them, should not take it.
- People with a current or recent stomach ulcer or bleeding should not take it.
- It is generally avoided in people with severe heart failure, severe kidney problems or severe liver problems.
- It is generally avoided in later pregnancy, and used with caution in older people.
Monitoring
- Reviewing how well pain and inflammation are controlled, using the lowest effective amount.
- Checking blood pressure and kidney function, particularly with long-term use or in those at risk.
- Watching for signs of stomach irritation or bleeding.
Side effects
- Indigestion, stomach upset or nausea.
- Stomach ulcers or bleeding, which can be serious.
- Effects on the kidneys, fluid retention and raised blood pressure.
- A small increased risk of heart attack and stroke, especially with higher amounts or long-term use.
Key interactions
- It adds to the bleeding risk of blood thinners such as warfarin and of other NSAIDs, including aspirin.
- It can reduce the effect of some blood pressure medicines and add to kidney risks with certain combinations.
- It can raise the levels of some medicines such as lithium and methotrexate, so tell your prescriber what you take.
Available as: Tablets taken by mouth.
Answers
Diflunisal: frequently asked questions
What is diflunisal used for?
It is an NSAID painkiller, related to aspirin, used to relieve pain and inflammation, including in conditions such as osteoarthritis and rheumatoid arthritis.
Can I take it if I am allergic to aspirin?
No. Diflunisal is related to aspirin, so it should not be used by anyone who has had an allergic reaction to aspirin or another NSAID, such as wheezing or a rash.
Why should I take it with food?
Like other NSAIDs, it can irritate the stomach and cause ulcers or bleeding, so taking it with or after food helps reduce stomach upset.
Does it affect the heart or kidneys?
Like other NSAIDs, it can affect the kidneys and carries a small increased risk of heart and circulation problems, so it is used at the lowest effective amount for the shortest time.
What warning signs should I watch for?
Report black stools, vomiting blood or severe stomach pain urgently, as these can be signs of stomach bleeding.
The wider class
About Non-steroidal anti-inflammatory drug (salicylate-related)
Diflunisal belongs to the non-steroidal anti-inflammatory drug (salicylate-related) 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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