Nintedanib: Uses, Side Effects, and Warnings

Nintedanib is a prescription medication that slows the scarring process in the lungs, approved for three forms of fibrosing lung disease and, in some countries, for a type of lung cancer. Sold under the brand name Ofev for lung fibrosis and Vargatef for cancer, it works by blocking growth-factor signals that drive both scar tissue formation and new blood vessel growth. The drug does not cure fibrotic lung disease, but across multiple large trials it has roughly halved the rate at which patients lose lung capacity over a year. That benefit comes alongside a well-known set of side effects, most prominently diarrhea, plus several serious risks that require ongoing monitoring.

How Nintedanib Works

Nintedanib belongs to a class of drugs called tyrosine kinase inhibitors. It blocks three receptor families that fibroblasts and blood-vessel cells rely on to proliferate and lay down collagen: platelet-derived growth factor (PDGF) receptors, fibroblast growth factor (FGF) receptors, and vascular endothelial growth factor (VEGF) receptors.¹ By jamming these signals simultaneously, nintedanib dials down both fibroblast activity and the blood-vessel remodeling that feeds scar tissue. In laboratory models, the drug has been shown to reduce collagen buildup and suppress the expression of fibrosis-related genes.²

This triple-receptor blockade is also the source of many of the drug’s side effects. VEGF, for instance, is not just a fibrosis driver; it maintains healthy blood vessels and the gut lining. Inhibiting it system-wide explains why nintedanib can cause problems ranging from bleeding to gastrointestinal perforation, issues shared by other drugs in the tyrosine kinase inhibitor family.

Approved Uses

Nintedanib has regulatory approval for three lung-related conditions, and in parts of Europe for a fourth. Understanding which disease you or a family member is being treated for matters, because the dose, the expected benefit, and even the brand name differ.

Idiopathic Pulmonary Fibrosis

The drug’s flagship indication is idiopathic pulmonary fibrosis (IPF), a progressive scarring of the lungs with no identifiable cause. The landmark INPULSIS trials, published in the New England Journal of Medicine, showed that nintedanib slowed the annual decline in forced vital capacity (FVC, a key measure of how much air your lungs can move) by roughly 125 mL per year in one trial and about 94 mL per year in the other, compared with placebo.³ Pooled data from the earlier TOMORROW trial and the INPULSIS trials put the average benefit at about 110 mL per year of preserved lung function.⁴ The standard dose for IPF is 150 mg taken twice daily with food.

Systemic Sclerosis-Associated Interstitial Lung Disease

Systemic sclerosis (scleroderma) can cause its own form of lung scarring. In the SENSCIS trial, nintedanib reduced the rate of FVC decline in these patients by about 44% versus placebo, with a between-group difference of roughly 41 mL per year.⁵ Further analysis showed this translated into a clinically meaningful reduction in disease progression.⁶ The absolute numbers look smaller than the IPF trials because scleroderma patients tend to lose lung function more slowly at baseline, so a 44% reduction represents a proportionally similar benefit.

Other Progressive Fibrosing Interstitial Lung Diseases

A number of other conditions can cause progressive lung scarring, including chronic hypersensitivity pneumonitis, autoimmune-related ILDs, and unclassifiable fibrotic disease. The INBUILD trial demonstrated that nintedanib’s benefit extends across these varied diagnoses. A meta-analysis pooling four placebo-controlled trials found that nintedanib cut the rate of FVC decline by about 51% over 52 weeks regardless of the specific underlying fibrotic diagnosis, with no meaningful difference in its effect across the patient populations studied.⁷

Non-Small-Cell Lung Cancer

In the European Union and several other markets, nintedanib is approved in combination with docetaxel chemotherapy as a second-line treatment for advanced non-small-cell lung cancer (NSCLC) of the adenocarcinoma subtype. The LUME-Lung 1 trial found that adding nintedanib to docetaxel improved progression-free survival modestly (median 3.4 versus 2.7 months). For patients with adenocarcinoma, the overall survival benefit was more substantial: median survival of about 12.6 months versus 10.3 months.⁸ This oncology indication is not approved in the United States, so it may come up only if you are treated outside the U.S. or in a clinical trial.

Common Side Effects

Diarrhea is the side effect that defines daily life on nintedanib. In clinical trials for IPF, about two-thirds of patients receiving the drug reported diarrhea at some point. A real-world study found that roughly 35% of patients developed diarrhea graded as moderate or worse, and about 13% ultimately had to stop treatment because of it.⁹ The same study identified low body mass index as a risk factor for developing significant diarrhea and found that concurrent use of a corticosteroid like prednisolone seemed to offer some protection.

Beyond diarrhea, nausea, vomiting, decreased appetite, and abdominal pain are common enough that most prescribers discuss them before starting the drug. Weight loss can follow from the combination of reduced appetite and persistent GI symptoms. These side effects tend to appear within the first few months and, for many patients, lessen over time. The practical advice specialists emphasize is to treat diarrhea proactively with anti-diarrheal medications rather than waiting to see if it worsens, and to stay in contact with the prescribing team rather than stopping the drug on your own.¹⁰

Liver enzyme elevations also occur frequently. Most are mild and picked up on routine blood tests before a patient feels anything. A smaller proportion are clinically significant, which is why liver function testing is standard before and during treatment.

Serious Warnings

Several risks go beyond routine side effects and require specific vigilance from both patients and their doctors.

Liver Injury

Drug-induced liver injury with nintedanib has been flagged as a concern since the premarketing clinical trials. A pharmacovigilance study found that liver-injury reports for nintedanib were disproportionately higher than for pirfenidone, the other major antifibrotic drug. About a third of the liver-injury cases led to hospitalization, and over a third required stopping the drug.¹¹ The prescribing label calls for liver function tests before treatment starts, monthly for the first three months, and periodically afterward. If enzyme levels rise substantially, dose reduction or temporary interruption is the standard approach, with permanent discontinuation reserved for severe or persistent elevations. Patients with moderate or severe liver impairment (Child-Pugh B or C) should not take nintedanib at all. For those with mild impairment, a reduced dose of 100 mg twice daily is recommended when the indication is IPF.¹²

Cardiovascular Risk

Because nintedanib inhibits VEGF and PDGF pathways, which play roles in maintaining healthy blood vessels and stabilizing atherosclerotic plaques, there has been concern about heart attacks and other cardiovascular events. In the pooled TOMORROW and INPULSIS data, the rate of heart attacks among patients with high baseline cardiovascular risk was about 3 per 100 patient-years in the nintedanib group compared with roughly 1.2 per 100 patient-years in the placebo group.¹³ That said, the rate of broader major adverse cardiovascular events (MACE, a composite that includes heart attack, stroke, and cardiovascular death) was similar between the nintedanib and placebo groups regardless of baseline risk level.

Researchers have debated whether the heart-attack signal reflects the drug itself or simply the clustering of cardiovascular risk factors that IPF patients tend to carry. A review in the British Journal of Clinical Pharmacology argued that the pharmacological mechanism, particularly VEGF inhibition’s role in plaque biology and the heart’s response to low oxygen, could plausibly contribute to the risk, and that lessons from cardio-oncology should guide monitoring.¹⁴ In practice, most specialists manage this by ensuring cardiovascular risk factors are well controlled before starting nintedanib and by monitoring patients with known heart disease more closely.

Bleeding

VEGF inhibition can impair the blood-vessel repair mechanisms your body uses after injury, and nintedanib carries a theoretical bleeding risk. Real-world data has been mixed. In a Central European registry study, the incidence of bleeding among nintedanib-treated patients was meaningfully higher than among those on pirfenidone, though the absolute number of bleeding events was small and most were mild or moderate.¹⁵ Patients on blood thinners present a particular challenge, since clinical trials largely excluded people taking anticoagulants. When anticoagulation is necessary alongside nintedanib, direct oral anticoagulants may be the safer pairing, especially with drug-level monitoring in high-risk patients.¹⁶

Gastrointestinal Perforation

Rarely, nintedanib has been associated with perforation of the stomach or intestines, reported at about 1 event per 1,000 patient-years in global pharmacovigilance data.¹⁷ Risk factors include prior abdominal surgery, long-term corticosteroid use, and especially the concurrent use of other drugs that also inhibit VEGF signaling. A case report documented gastric perforation in a patient receiving nintedanib alongside ramucirumab, another VEGF-targeting agent, suggesting that stacking anti-angiogenic drugs amplifies this risk substantially.¹⁸ GI perforation is a medical emergency, so patients are advised to seek immediate care for sudden, severe abdominal pain.

Drug Interactions and Metabolism

Nintedanib is processed in the body partly through a transport protein called P-glycoprotein (P-gp). Drugs that strongly inhibit P-gp can raise nintedanib levels in the blood. In a pharmacokinetic study, co-administration with ketoconazole (a potent P-gp inhibitor and antifungal) increased nintedanib blood levels by about 60%, while rifampicin (a P-gp inducer used for tuberculosis) cut levels roughly in half.¹⁹ What this means in practice: if you start or stop a strong P-gp inhibitor or inducer while on nintedanib, your prescriber will likely need to adjust dosing or increase monitoring. Common P-gp inhibitors include certain antifungals, some antibiotics like erythromycin, and several heart rhythm drugs. St. John’s wort is a notable P-gp inducer to watch for on the supplement side.

How Nintedanib Compares to Pirfenidone

Pirfenidone (brand name Esbriet) is the other major antifibrotic approved for IPF, and the question patients most often ask is which drug works better. The honest answer is that they are roughly equivalent in slowing lung function decline, but they have meaningfully different side-effect profiles. A systematic review found the two drugs showed similar antifibrotic efficacy after six months.²⁰

A Bayesian network meta-analysis offered a more granular comparison: both drugs significantly reduced the risk of a 10% or greater decline in FVC compared with placebo, though pirfenidone appeared somewhat more effective on that specific measure. Neither drug significantly reduced one-year mortality.²¹ A separate meta-analysis confirmed similar survival outcomes between the two and highlighted the trade-off in side effects: nintedanib carries much higher odds of diarrhea and liver-function abnormalities, while pirfenidone is far more likely to cause photosensitivity (severe sunburn reactions) and skin rashes.²²

In practice, the choice between the two often depends on which side-effect profile is more tolerable for a given patient. Someone who works outdoors in strong sunlight might lean toward nintedanib to avoid photosensitivity. Someone already prone to GI trouble or with liver concerns might do better on pirfenidone. Switching from one to the other after intolerable side effects is common and does not seem to compromise disease control.

Real-World Tolerability and Discontinuation

Trial data always presents a rosier picture than what happens in everyday clinical practice, and nintedanib is no exception. In a large Japanese post-marketing surveillance study, nearly 65% of patients had stopped nintedanib within 24 months, with adverse events being the most common reason for discontinuation.²³ A smaller real-world cohort found that only about 41% of patients maintained the full dose, while 31% needed a dose reduction and 28% stopped treatment entirely due to side effects, mostly GI and liver-related.²⁴

These numbers can look discouraging, but context matters. Many patients who reduce from 150 mg twice daily to 100 mg twice daily still maintain some treatment benefit. The disease itself is progressive and life-limiting, so even a drug that is hard to tolerate may be worth persisting with if it is slowing the decline. Close communication with a pulmonologist, early and aggressive management of diarrhea, and willingness to try dose adjustments before quitting altogether tend to keep more patients on therapy.

Quality of Life on Treatment

A drug that slows lung scarring on paper does not automatically make patients feel better day to day, and this is an area where nintedanib’s track record is mixed. In the INPULSIS trials, nintedanib did not produce a meaningful improvement in overall quality-of-life scores as measured by the St George’s Respiratory Questionnaire across the full study population. However, among patients who already had more advanced disease, nintedanib did slow the worsening of several patient-reported outcomes, particularly activity limitations.²⁵ A Japanese subset analysis of the INBUILD trial found that patients on placebo experienced larger increases in symptom burden, including fatigue and dyspnea scores, than those on nintedanib, and that cough actually improved in the nintedanib group while worsening in the placebo group.²⁶

The takeaway is that nintedanib’s benefit is more about slowing decline than reversing symptoms. Patients starting the drug should expect that their lung function will still decline, just less quickly. Feeling the same or slightly worse over time does not mean the drug is not working; it may mean things would have deteriorated faster without it. That is a psychologically difficult proposition, and patient support programs and pulmonary rehabilitation can help bridge the gap between what the numbers show and how people actually feel.

Research Into Post-COVID Lung Fibrosis

After severe COVID-19, some patients develop persistent lung scarring that resembles other forms of fibrotic ILD, which prompted interest in whether nintedanib could help. An early observational study showed that patients who received nintedanib had greater improvements in oxygen levels than a control group, generating cautious optimism.²⁷ However, a subsequent randomized, double-blind, placebo-controlled trial painted a different picture: both the nintedanib and placebo groups improved substantially over 180 days, with no significant difference between them in lung function, imaging, walking distance, or symptom scores.²⁸ The likely explanation is that post-COVID lung changes, unlike IPF, can resolve spontaneously over time, so a drug designed to slow progression has little to add when the natural trajectory is already improving. Additional randomized trials are ongoing to see whether specific subgroups, perhaps those whose fibrosis does not improve on its own, might still benefit.²⁹

Tracking Treatment Response With Blood Biomarkers

One of the frustrating aspects of antifibrotic therapy is that there is no quick blood test to tell you whether the drug is working. FVC measurements take months to show a trend, and by the time a decline is obvious it may be too late to switch strategies. Researchers are actively trying to change that. The INMARK trial found that rising blood levels of a collagen-degradation marker called CRPM over the first 12 weeks were associated with disease progression over the following year, suggesting it could serve as an early warning signal.³⁰

A more recent pilot study examined a panel of five blood proteins in patients with progressive fibrosing ILD treated with nintedanib. Over 12 months of treatment, the protein patterns shifted from a fibrotic profile back toward what was seen in healthy subjects, and several individual markers showed increasing ability to distinguish responders from non-responders as treatment duration increased.³¹ These are preliminary findings from small studies, not ready for routine clinical use. But they represent a meaningful push toward personalized monitoring that could, eventually, let doctors know within weeks rather than months whether a given patient’s fibrosis is actually responding to therapy.