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leflunomide

Sold as Arava. Class: Dihydroorotate dehydrogenase (DHODH) inhibitors. First FDA approval 09/10/1998: 28 years on the US market.

This grade answers one narrow question: how strong is the public evidence and safety record behind this drug, and how clean is its money trail and court record? It is not a verdict on whether the drug is right for you.

C

Score breakdown (70/100)

Safety ×35%
D
Evidence ×25%
D
Regulatory ×15%
A
Money & lawsuits ×15%
A
Options ×10%
A

Safety: 55

Evidence: 50

Regulatory history: 95

Money & lawsuits: 100

Options: 90

FDA boxed warning

WARNING: EMBRYO-FETAL TOXICITY and HEPATOTOXICITY WARNING: EMBRYO-FETAL TOXICITY and HEPATOTOXICITY See full prescribing information for complete boxed warning. Embryo-Fetal Toxicity Teratogenicity and embryo-lethality occurred in animals administered leflunomide. ( 5.1 , 8.1 ) Exclude pregnancy prior to initiating ARAVA therapy. ( 5.1 , 8.3 ) Advise use of effective contraception in females of reproductive potential during treatment and during a drug elimination procedure. ( 5.1 , 5.3 , 8.3 ) Stop ARAVA and use an accelerated drug elimination procedure if the patient becomes pregnant. ( 5.1 , 5.3 , 8.1 ) Hepatotoxicity Severe liver injury and fatal liver failure have been reported. ( 5.2 ) Avoid ARAVA use in patients with pre-existing liver disease, or those with serum alanine aminotransferase (ALT) >2 × ULN. ( 5.2 , 8.6 ) Use caution when ARAVA is given with other potentially hepatotoxic drugs. ( 5.2 ) Monitor ALT levels. Interrupt ARAVA treatment if ALT elevation >3-fold ULN. If likely leflunomide-induced, start accelerated drug elimination procedure and monitor liver tests weekly until normalized. ( 5.2 , 5.3 ) Embryo-Fetal Toxicity ARAVA is contraindicated for use in pregnant ...

What the FDA label says

Approved uses

is indicated for the treatment of adults with active rheumatoid arthritis (RA). ARAVA is a pyrimidine synthesis inhibitor indicated for the treatment of adults with active rheumatoid arthritis. ( 1 )

Contraindications

is contraindicated in: Pregnant women. ARAVA may cause fetal harm. If a woman becomes pregnant while taking this drug, stop ARAVA, apprise the patient of the potential hazard to the fetus, and begin a drug elimination procedure [see Warnings and Precautions (5.1 , 5.3) and Use in Specific Populations (8.1) ] . Patients with severe hepatic impairment [see Warnings and Precautions (5.2) ] . Patients with known hypersensitivity to leflunomide or any of the other components of ARAVA. Known reactions include anaphylaxis [see Adverse Reactions (6.1) ] . Patients being treated with teriflunomide [see Drug Interactions (7) ] . Pregnancy. ( 4 , 5.1 , 8.1 ) Severe hepatic impairment. ( 4 , 5.2 ) Hypersensitivity to ARAVA or any of its inactive components. ( 4 ) Current teriflunomide treatment. ( 4 )

Warnings and precautions

After stopping ARAVA, it is recommended that an accelerated drug elimination procedure be used to reduce the plasma concentrations of the active metabolite, teriflunomide. ( 5.3 ) Severe infections (including sepsis), pancytopenia, agranulocytosis, and thrombocytopenia: Stop ARAVA and use accelerated elimination procedure. Do not start ARAVA in patients with active infection. Monitor CBCs during treatment with ARAVA. ( 5.4 ) Stevens-Johnson syndrome and toxic epidermal necrolysis, drug reaction with eosinophilia and systemic symptoms (DRESS): Stop ARAVA and use accelerated elimination procedure. ( 5.5 ) Skin ulcers: If skin ulcer is suspected, discontinue leflunomide treatment and consider an accelerated drug elimination procedure. ( 5.6 ) Peripheral neuropathy: If patient develops symptoms consistent with peripheral neuropathy, evaluate patient and consider discontinuing ARAVA. ( 5.8 ) Interstitial lung disease: May be fatal. New onset or worsening symptoms may necessitate discontinuation of ARAVA and initiation of accelerated elimination procedure. ( 5.9 ) Increased blood pressure: Monitor and treat. ( 5.11 ) 5.1 Embryo-Fetal Toxicity ARAVA may cause fetal harm when administered ...

Adverse reactions (label)

The following serious adverse reactions are described elsewhere in the labeling: Hepatotoxicity [see Warnings and Precautions (5.2) ] Immunosuppression [see Warnings and Precautions (5.4) ] Bone marrow suppression [see Warnings and Precautions (5.4) ] Serious infections [see Warnings and Precautions (5.4) ] Stevens-Johnson syndrome, toxic epidermal necrolysis, and drug reactions with eosinophilia and systemic symptoms [see Warnings and Precautions (5.5) ] Skin ulcers [see Warnings and Precautions (5.6) ] Peripheral neuropathy [see Warnings and Precautions (5.8) ] Interstitial lung disease [see Warnings and Precautions (5.9) ] The most commonly reported adverse reactions (≥10%) regardless of relation to ARAVA treatment were diarrhea, respiratory infection, nausea, headache, rash, abnormal liver enzymes, and dyspepsia. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact sanofi-aventis U.S. LLC at 1-800-633-1610 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical studies are conducted under widely varying conditions, adverse reaction rates observed in the clinical studies of a drug cannot be directly compared to rates in the clinical st...

Recent major label changes

Warnings and Precautions, Skin Ulcers ( 5.6 ) 6/2024

Source: FDA SPL label for Arava (sanofi-aventis U.S. LLC), effective 20250604. Full label on DailyMed.

Side-effect reports sent to the FDA

These are counts of reports people filed, not rates of harm. Anyone can file one, and nobody checks whether the drug was the cause. Millions of doses are taken for every report sent, so the useful part is how this drug compares with the average across all drugs.

90,432reports that mention this drug
90,340of those blame this drug, not another one the person was taking
86%of reports describe a serious outcome, such as a hospital stay (average for all drugs: 57%)
8.9%of reports include a death, from any cause (average for all drugs: 9.1%)

Problems reported most often

Drug Ineffective · 38,270Rheumatoid Arthritis · 25,388Pain · 20,113Arthralgia · 16,673Drug Intolerance · 16,350Joint Swelling · 15,929Fatigue · 15,326Rash · 13,431Off Label Use · 12,333Contraindicated Product Administered · 12,135Abdominal Discomfort · 12,054Alopecia · 11,914Arthropathy · 11,105Condition Aggravated · 10,609Swelling · 10,539

Reports per year

20192020202120222023202420252026
11,24515,5159,5388,1355,3616,3355,3361,845

23,298 reports blaming this drug for every million Medicare prescriptions filled, which is 8.4× the typical drug on this site. (13,478 reports in 2024–2026, against 578,502 Medicare fills in one year. This is the one number here that accounts for how many people take the drug.)

Source: the FDA's Adverse Event Reporting System (FAERS). Reports are voluntary and unverified. Drugs that are prescribed a lot, in the news, or in lawsuits attract more reports, so the percentages are compared with the whole database to correct for that partly, not fully.

Recalls and regulatory record

0recall actions on file
1 / 12brand / generic applications
1label changes since 2021
NoREMS program

Evidence base

84randomized trials (PubMed)
19systematic reviews
141registered trials
46%of completed trials posted results
11%terminated or withdrawn
32%industry-funded

Independent Cochrane reviews

Counts measure how much evidence exists and how transparent it is, not how big the benefit is. For that, ask your prescriber: if 100 people like me took this, how many would get better because of it, and how many would be harmed? (Doctors call these the "number needed to treat" and "number needed to harm.") It differs by condition and is the number drug ads leave out. Sources: PubMed, ClinicalTrials.gov.

Money and lawsuits

In 2024, drug companies reported $0 in payments to US physicians and hospitals tied to this drug across 0 transactions.

No pending federal MDL names this drug or its brands.

Not named in any federal pharmaceutical settlement of $100M or more on record.

Sources: CMS Open Payments (Sunshine Act); Judicial Panel on Multidistrict Litigation pending docket list; DOJ settlements as tabulated on Wikipedia with links to the primary record. State-court and individual suits are not included.

Who takes it and what it costs

147,574Medicare Part D patients (2024)
578,502prescriptions filled
$62average cost per fill
$36Mtotal Medicare spend
ProductFills$/fill
Leflunomide578,121$60
Arava381$2,399

Same-class alternatives

teriflunomide

Same ATC pharmacological class, graded ones first, best grade at the top. Being in the same class does not make them interchangeable for your condition; it makes them worth asking about.

Questions to ask your prescriber

  1. This drug carries a boxed warning. Which specific risk does it cover, and does it apply to me?
  2. The most-reported problems in FDA's adverse event data are rheumatoid arthritis, pain, arthralgia. How would we recognize and handle those?
  3. Why this one over teriflunomide? What would make you pick one of those instead?
  4. What result are we expecting, by when, and what is the plan if it does not happen?
  5. If 100 people like me took this drug, how many would actually get better because of it, and how many would be harmed by it? (Doctors call these the number needed to treat and the number needed to harm.)