Approved indication: In the United States, pirfenidone is FDA-approved for the treatment of idiopathic pulmonary fibrosis (IPF) in adults, with the goal of slowing disease progression.

Off-label uses (not FDA-approved):

• Some clinicians may use pirfenidone experimentally for other progressive fibrosing interstitial lung diseases (ILDs), such as connective tissue disease–associated ILD or chronic hypersensitivity pneumonitis, based on small studies and observational data.
• Evidence for these off-label uses is limited and less robust than for IPF, so benefit is uncertain and decisions are individualized.

Efficacy expectations:

• Pirfenidone does not cure IPF or restore lost lung function; it is intended to slow the rate of decline in lung capacity.
• Benefits are usually seen over months as a smaller drop in forced vital capacity (FVC) and fewer patients experiencing large declines in lung function or death compared with no antifibrotic treatment.
• In head-to-head trials pirfenidone has not clearly been shown superior or inferior to the other approved IPF antifibrotic, nintedanib; choice between them is often based on side-effect profiles, other medical conditions, and patient preference.

Typical dosing and how to take it:

• For adults with IPF, the target maintenance dose is 801 mg by mouth three times daily (total 2403 mg/day), taken with food at roughly the same times each day (for example, with breakfast, lunch, and dinner).
• To reduce side effects, the dose is titrated over 14 days: days 1–7 at 267 mg three times daily, days 8–14 at 534 mg three times daily, then from day 15 onward at 801 mg three times daily if tolerated.
• Capsules or tablets should be swallowed whole with water; they should not be split, crushed, or chewed.

Special dosing instructions:

• Doctors may temporarily lower the dose, pause treatment, or slowly re-titrate if you develop troublesome side effects or abnormal liver tests.
• Use is generally avoided in severe liver disease or in severe kidney disease requiring dialysis; people who smoke should be strongly encouraged to quit because smoking can lower pirfenidone levels and reduce effectiveness.
• When strong or moderate CYP1A2 inhibitor drugs (such as fluvoxamine or high-dose ciprofloxacin) are needed, your pirfenidone dose may have to be reduced according to your prescriber’s instructions.

Missed doses and overdose:

• If you miss a dose, take it with food as soon as you remember, but skip it if it is almost time for your next scheduled dose; do not take two doses at once and do not take more than three doses in a single day.
• If you take more than the prescribed amount, contact your doctor, poison control center, or seek emergency medical care right away, bringing the medication container with you if possible.

Common side effects:

• Gastrointestinal problems such as nausea, indigestion, diarrhea, vomiting, decreased appetite, and weight loss are very common, especially during dose increases and when doses are not taken with food.
• Skin reactions including rash and sun sensitivity (photosensitivity), as well as fatigue, dizziness, and headache, also occur frequently; these are often mild to moderate and may improve with sun protection, dose adjustment, or time.

Serious or rare adverse effects needing immediate medical attention:

• Signs of liver injury such as unusual fatigue, loss of appetite, right upper abdominal pain, dark urine, or yellowing of the skin or eyes.
• Severe skin reactions or blistering rash, or a very intense sunburn-like reaction after limited sun exposure.
• Swelling of the face, lips, tongue, or throat; trouble breathing; or severe allergic reactions.

Warnings and precautions:

• Liver disease: Use with caution in patients with liver problems; liver blood tests are required before starting, monthly for the first 6 months, then every 3 months and as needed, and the drug may need to be reduced, stopped temporarily, or discontinued if tests become abnormal.
• Kidney disease: Use carefully in moderate kidney impairment; it is generally not recommended in severe kidney impairment or in patients on dialysis.
• Pregnancy and breastfeeding: There are limited data in pregnant or breastfeeding people; animal studies show potential risk to the fetus, so use is typically avoided unless the potential benefit clearly justifies the risk, and breastfeeding may need to be stopped if treatment is necessary.
• Age limits: Safety and effectiveness are established in adults; it is not known if pirfenidone is safe or effective in children.
• Sun exposure: Patients should avoid or minimize direct sunlight and tanning beds, use broad-spectrum sunscreen, and wear protective clothing to reduce photosensitivity reactions.

Relative safety compared with other options: Compared with nintedanib, the other main IPF antifibrotic, pirfenidone tends to cause more photosensitivity and certain gastrointestinal symptoms but less diarrhea; overall serious-risk profiles (especially for liver toxicity) are broadly similar, and the safer choice depends on an individual patient’s other health conditions and medications.

Reporting side effects and staying updated: Patients and caregivers can report suspected side effects to the FDA’s MedWatch program (by phone or online) and can check the FDA and manufacturer websites for the latest safety communications, label changes, and risk information.

Drug and supplement interactions:

• Strong CYP1A2 inhibitors (for example, fluvoxamine, some quinolone antibiotics like enoxacin) can greatly increase pirfenidone levels and are generally avoided or require substantial pirfenidone dose reduction.
• Moderate CYP1A2 inhibitors (such as higher-dose ciprofloxacin) may also require lowering the pirfenidone dose and close monitoring for side effects.
• Cigarette smoking induces CYP1A2, lowering pirfenidone blood levels and potentially making it less effective; patients are urged to stop smoking and avoid starting again while on therapy.
• Alcohol can add to liver stress; heavy alcohol use should be avoided, and even moderate use should be discussed with the prescriber.
• There are no major known interactions with most common over-the-counter medicines or vitamins, but patients should always review all prescription drugs, OTC medicines, and herbal supplements (such as St. John’s wort) with their clinician or pharmacist.

Food, sun, and procedure considerations:

• Pirfenidone must be taken with food to help reduce nausea and dizziness; no specific food restrictions are required beyond this.
• Because of photosensitivity risk, patients should limit sun exposure and avoid tanning beds, which may also reduce confusion with rashes seen during imaging contrast reactions.
• No specific interactions are known with common imaging contrast agents, but inform radiology staff that you are taking pirfenidone and provide a list of all medicines.

Conditions and co-medications that require extra caution:

• Pre-existing liver disease, a history of drug-induced liver injury, or concurrent use of other hepatotoxic drugs increases the risk of liver problems and may require more frequent blood tests or alternative therapy.
• Moderate to severe kidney impairment, especially if dialysis is required, may make pirfenidone inappropriate or require careful specialist review.
• Prior serious allergic reactions or angioedema to pirfenidone are reasons not to use the drug again.

Monitoring needs: Before starting pirfenidone and during treatment, patients should have regular liver function blood tests (baseline, monthly for 6 months, then every 3 months and as needed), periodic assessments of weight and symptoms, and routine lung function tests as part of their IPF care plan.

Q: What is pirfenidone used for?
A: Pirfenidone is a prescription medicine used in adults to slow the progression of idiopathic pulmonary fibrosis (IPF), a chronic scarring disease of the lungs.

Q: How long will I need to take pirfenidone?
A: Most people who tolerate pirfenidone continue it long term, as long as it appears to be helping slow lung function decline and side effects remain manageable.

Q: When should I take my doses?
A: Take pirfenidone three times a day with food, spaced roughly with breakfast, lunch, and dinner, and try to take it at the same times every day.

Q: Can I go out in the sun while on pirfenidone?
A: You can be outdoors, but you should minimize direct sun exposure, use broad-spectrum sunscreen, and wear protective clothing and hats because pirfenidone can make your skin more sensitive to sunlight.

Q: Is pirfenidone the same as a steroid or chemotherapy?
A: No, pirfenidone is an antifibrotic and anti-inflammatory medicine, not a steroid or traditional chemotherapy drug, and it works specifically to slow lung scarring in IPF.

Q: What happens if I feel worse while taking pirfenidone?
A: If your breathing, cough, or side effects suddenly worsen, contact your healthcare provider promptly so they can evaluate whether it is a flare of IPF, an infection, a drug side effect, or another issue and adjust treatment as needed.

Storage: Store pirfenidone at room temperature (about 68°F to 77°F / 20°C to 25°C), in the original tightly closed container, protected from moisture and direct light, and keep it out of reach of children and pets.

Disposal: Do not flush pirfenidone down the toilet or pour it into drains; use a community drug take-back program when available, or ask a pharmacist how to dispose of it safely in household trash (for example, by mixing the pills with an undesirable substance, sealing in a bag or container, and removing any personal information from the prescription label).