Nabumetone
- Generic name
- nabumetone
- Brand names
- Relafen
- Drug class
- Nonsteroidal Anti-Inflammatory Drug (NSAID) — prodrug
- Form
- Tablet (500 mg, 750 mg)
- Route
- Oral
- Legal status
- Prescription only. Confirmed Authorised in the United States, United Kingdom, and Canada; Australia and New Zealand could not be independently confirmed in this review.
Availability and supply rules vary by country
Trade names by country: United States · United Kingdom · Canada
Australia: · Full directory
What nabumetone is and how it works
Nabumetone is an NSAID used for the relief of signs and symptoms of osteoarthritis and rheumatoid arthritis. A real, significant correction from outdated information: nabumetone is approved only for osteoarthritis and rheumatoid arthritis — not for ankylosing spondylitis or general acute pain, which are sometimes listed for this medicine in error. (1)
A real, favorable distinguishing feature of nabumetone within the NSAID family is its comparatively low rate of serious stomach bleeding and ulcers in pooled clinical trial data, though it still carries the same class-wide GI, cardiovascular, and skin-reaction warnings as other NSAIDs.
Mechanism of action: how nabumetone works
Nabumetone is a nonselective NSAID prodrug; approximately 35% of an oral dose is converted in the liver to the active metabolite 6-methoxy-2-naphthylacetic acid (6MNA), which has a half-life of approximately 23 hours. The remainder is largely excreted as unidentified metabolites in urine. (1)
What nabumetone is used for
Osteoarthritis
Used for relief of the signs and symptoms of osteoarthritis. (1)
Rheumatoid arthritis
Used for relief of the signs and symptoms of rheumatoid arthritis. (1)
Before taking nabumetone
Do not take / not appropriate for
- Do not take nabumetone if you have had asthma, hives, or an allergic-type reaction after taking aspirin or another NSAID. (aspirin/NSAID-hypersensitivity reaction history) (1)
- Do not take nabumetone right before or after coronary artery bypass graft (CABG) heart surgery. (CABG surgery) (1)
Tell your clinician about
- Any heart, kidney, or liver disease.
- Any history of stomach ulcers or GI bleeding.
- All other medicines, especially aspirin, ACE inhibitors, diuretics, lithium, methotrexate, or warfarin.
- If you are pregnant, planning pregnancy, or breastfeeding.
How to take nabumetone
- Usual starting dose is 1000mg as a single daily dose, with or without food.
- Some people need 1500-2000mg per day, taken as a single dose or split into two doses. Doses above 2000mg/day have not been studied.
- In moderate kidney impairment, the maximum recommended starting dose is 750mg once daily; in severe kidney impairment, it is 500mg once daily.
- Because nabumetone is a prodrug, it can take longer to reach its full effect than some other NSAIDs — the active metabolite has a half-life of about 23 hours.
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)
Missed dose
If you miss a dose, contact your clinician or pharmacist for guidance on your specific schedule. Do not take a double dose without their advice.
Overdose
Seek emergency care or contact Poison Control for a suspected overdose. (1)
Side effects
Nabumetone shares the general side-effect profile of other NSAIDs, though pooled trial data show a comparatively low rate of serious GI bleeding.
Diarrhea
What to notice: Reported in about 14% of patients.
What to do: Mention persistent symptoms to your clinician. (1)
Dyspepsia (indigestion)
What to notice: Reported in about 13% of patients.
What to do: Mention persistent symptoms to your clinician. (1)
Abdominal pain
What to notice: Reported in about 12% of patients.
What to do: Mention persistent symptoms to your clinician. (1)
Dizziness, headache, fatigue, insomnia, itching, rash, fluid retention, ringing in the ears
What to notice: Each reported in roughly 3-9% of patients.
What to do: Mention persistent or bothersome symptoms to your clinician. (1)
Serious skin reactions
What to notice: Widespread rash, blistering, or peeling skin (Stevens-Johnson syndrome or toxic epidermal necrolysis).
What to do: Seek emergency care immediately. (1)
GI bleeding or ulcer
What to notice: Black or bloody stools, vomiting blood, severe stomach pain.
What to do: Seek emergency care immediately. (1)
Serious warnings
Cardiovascular risk (class-wide) — serious
Symptoms: Chest pain, shortness of breath, sudden weakness, slurred speech.
Action: Seek emergency care immediately. (1)
GI bleeding/ulceration — serious
Symptoms: Black or bloody stools, vomiting blood, severe abdominal pain.
Action: Seek emergency care immediately. Nabumetone's pooled-trial GI-bleeding rate is comparatively low among NSAIDs, but the risk is not eliminated. (1)
Serious skin reactions — emergency
Symptoms: Widespread rash, blistering, or skin peeling, which can appear without warning.
Action: Seek emergency care immediately. (1)
Interactions
| Medicine or test | Effect | Action |
|---|---|---|
| Aspirin | Increases the risk of adverse effects; concomitant use is not recommended. | Discuss with your clinician before combining. (1) |
| ACE inhibitors | May reduce their blood-pressure-lowering effectiveness. | Your clinician may monitor blood pressure. (1) |
| Diuretics (furosemide, thiazides) | May reduce the natriuretic (salt-excreting) effect of these medicines. | Your clinician may monitor blood pressure and fluid status. (1) |
| Lithium | Can raise lithium blood levels. | Your clinician will monitor lithium levels more closely. (1) |
| Methotrexate | May enhance methotrexate toxicity. | This combination requires careful clinician oversight. (1) |
| Warfarin | Synergistic effect on GI bleeding risk. | This combination requires careful clinician oversight. (1) |
Pregnancy, breastfeeding, kidney/liver function, age
Renal impairment
In moderate kidney impairment, the maximum recommended starting dose is 750mg once daily; in severe kidney impairment, it is 500mg once daily. (1)
Older adults
Require more cautious dosing given a higher risk of GI bleeding. (1)
Pregnancy
Avoid NSAIDs, including nabumetone, starting at about 30 weeks of pregnancy because of a real risk of premature closure of the fetal ductus arteriosus. Between 20 and 30 weeks, use only if clearly needed, at the lowest effective dose for the shortest possible time. (1)
Breastfeeding
It is not known whether nabumetone or its active metabolite passes into human breast milk. The active metabolite has been found in rat milk. Discuss with your clinician whether to continue nursing based on your specific need for this medicine. (1)
Monitoring
Before starting
- Confirm the condition being treated is osteoarthritis or rheumatoid arthritis.
- Review heart, kidney, and liver health.
- Review any history of stomach ulcers or GI bleeding.
- Review other medicines, especially aspirin, ACE inhibitors, diuretics, lithium, methotrexate, and warfarin.
During treatment
- Watch for stomach pain, black stools, or vomiting blood.
- Watch for any new rash or skin changes — seek care immediately.
- Periodic monitoring may be recommended for those on long-term therapy or with kidney impairment.
Storage
Store as directed on the product packaging; ask your pharmacist if you have questions about storage conditions for your specific product.
Professional information
Clinician-facing context only. Indication scope is corrected to osteoarthritis and rheumatoid arthritis only per the current FDA label; ankylosing spondylitis and acute pain are not approved uses for this medicine.
United States
Indication: OA, RA only.
Dose summary: 1000mg single starting dose; 1500-2000mg/day if needed, single or divided; not studied above 2000mg/day.
Renal context: Max 750mg/day (moderate impairment); max 500mg/day (severe impairment). (1)
United Kingdom
Indication: Authorised — 8 real MHRA files, including a specific 500mg film-coated tablet product.
Dose summary: Not itemized in this pass.
Renal context: Not itemized. (3)
Canada
Indication: Authorised — 12 real DPD-listed products (500mg and 750mg strengths).
Dose summary: Not itemized in this pass.
Renal context: Not itemized. (2)
Australia
Indication: Unable to verify — a general S4 (Prescription Only) classification was found, but no specific ARTG registration number was independently confirmed.
Dose summary: Not itemized.
Renal context: Not itemized. (4)
New Zealand
Indication: Unable to verify — nabumetone appears only in aggregate Medsafe safety/committee reports, not in a dedicated product data sheet.
Dose summary: Not itemized.
Renal context: Not itemized. (5)
Hepatic guidance
As a hepatically-activated prodrug, nabumetone's conversion to its active metabolite depends on liver function; use with caution in hepatic impairment.
Overdose note
Supportive care and poison control guidance. (1)
Frequently asked questions
Is nabumetone approved for ankylosing spondylitis or acute pain?
No. The current FDA label for nabumetone approves it only for osteoarthritis and rheumatoid arthritis. It is not an approved treatment for ankylosing spondylitis or general acute pain. (1)
Is nabumetone easier on the stomach than other NSAIDs?
Pooled clinical trial data show a comparatively low rate of serious stomach bleeding and ulcers with nabumetone versus some other NSAIDs, but it still carries the same class-wide GI-bleeding warning, and the risk is not eliminated. (1)
Why is nabumetone described as a prodrug?
Nabumetone itself is largely inactive until the liver converts about 35% of a dose into its active form, 6-methoxy-2-naphthylacetic acid (6MNA), which has a long half-life of about 23 hours. (1)
What is the mechanism of action of nabumetone?
Nabumetone is a nonselective NSAID prodrug; approximately 35% of an oral dose is converted in the liver to the active metabolite 6-methoxy-2-naphthylacetic acid (6MNA), which has a half-life of approximately 23 hours. The remainder is largely excreted as unidentified metabolites in urine. (1)
What is the generic name of Nabumetone?
The generic name is nabumetone. It is sold under brand names including Relafen. (1)
What class of drug is nabumetone?
Nabumetone is classed as: Nonsteroidal Anti-Inflammatory Drug (NSAID) — prodrug. (1)
References
- Nabumetone Tablets, USP (RELAFEN) — prescribing informationDailyMed / FDA · United States · accessed 2026-07-27 · source 1
- DPD active-ingredient query for nabumetone (12 products)Health Canada DPD, public API · Canada · accessed 2026-07-27 · source 2
- NABUMETONE substance page (8 files)MHRA Products · United Kingdom · accessed 2026-07-27 · source 3
- Nabumetone described as S4 (Prescription Only) legal status in Australia, brand RelafenGeneral secondary reference (not a direct TGA ARTG query) · Australia · accessed 2026-07-27 · source 4
- Nabumetone appears only in aggregate Medsafe safety/committee reports (NSAID pregnancy and spontaneous-abortion reviews, MARC minutes), not as a registered product data sheetMedsafe (New Zealand), committee/safety reports only · New Zealand · accessed 2026-07-27 · source 5
Brand names by country
Single-ingredient nabumetone names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.
Priority countries
United States
- RELAFEN DS1000 mg · carwin pharmaceutical associates, llc
United Kingdom
- Nabumetone (generic) (3)MHRA licensed 8 files · 500 mg · multiple
Canada
- Nabumetone (generic, multiple manufacturers) (2)currently listed 12 real products · 500 mg, 750 mg · multiple