Femi Aremu, PharmD, is a professional pharmacist with experience in clinical and community pharmacy. He currently practices in Chicago, Illinois.

Pentoxifylline is a prescription medication used in adults to improve blood flow. Improved blood flow, in turn, helps carry more oxygen to your tissues and organs. It also reduces the pain experienced with intermittent claudication. Intermittent claudication is a common symptom of a blood flow issue called peripheral artery disease.

Pentoxifylline is in a class of drugs called hemorheologic agents. It works by reducing the thickness of the blood and making red blood cells more flexible. It used to be available under the brand names Pentoxil and Trental, which have been discontinued in the United States.

Pentoxifylline generic tablets are available in a white, oblong, 400 milligram extended-release tablet.

Brand Name: Pentoxil (discontinued), Trental (discontinued)

The Food and Drug Administration (FDA) approved pentoxifylline for treating intermittent claudication in adults.  Intermittent claudication is the most common symptom of peripheral artery disease.

Intermittent claudication causes leg pain, aches, heaviness, or cramps when walking or performing physical activity but that get better with rest. Peripheral artery disease (PAD) in the legs is the narrowing or blockage of the vessels that carry blood from the heart to the legs, caused by the buildup of plaque in the wall of arteries, which is called atherosclerosis.

Use this medicine exactly as directed by your healthcare provider. Follow the directions on the medication's label for how to take it. Don’t take more or less than prescribed. Ask a healthcare provider or pharmacist if you do not understand how to take your medications.

Take three times a day with meals to reduce an upset stomach. Do not crush, chew, or break this tablet. Swallow it whole. Do not stop taking this medication without talking to your healthcare provider first, even if you feel well.  

Store pentoxifylline capsules in a tightly sealed, light-resistant container at room temperature (about 68 degrees to 77 degrees Fahrenheit). Keep away from moisture and out of reach of children and pets. When traveling, transport the tablets in your carry-on or your checked baggage with their original label.

Pentoxifylline is sometimes prescribed to treat acute alcoholic hepatitis. This is not an FDA-approved use, and there is no evidence that pentoxifylline effectively treats this condition. Misusing this medicine can result in severe or life-threatening side effects. Always take it exactly as instructed by your healthcare provider.

Pentoxifylline enters the bloodstream within four hours and starts working. It is absorbed faster in the presence of food. While your symptoms may improve within two to four weeks, it is recommended that treatment continues for at least eight weeks.

This is not a complete list of side effects and others may occur. A healthcare provider can advise you on side effects. If you experience other effects, contact your healthcare provider. You may report side effects to the FDA at fda.gov/medwatch or 800-FDA-1088.

Common side effects of pentoxifylline include:

Call your healthcare provider right away if you have serious side effects. Call 911 immediately if your symptoms feel life-threatening or if you think you or someone else is having a medical emergency.

In some cases, chest pain and arrhythmia (irregular heartbeat) can occur with pentoxifylline. Let your healthcare provider know if you experience these side effects, as they can be severe.

Pentoxifylline may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your provider may send a report to the FDA'S MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

Certain factors may affect how you take this medication, such as:

Tell your healthcare provider if you are pregnant or plan to become pregnant while using this medication. It is unknown whether pentoxifylline will harm the fetus if taken during pregnancy. Your healthcare provider will advise you on how to continue with your treatment.

Pentoxifylline may harm a nursing baby by passing into breast milk. It would be best if you did not breastfeed while using pentoxifylline. You and your healthcare provider should decide to discontinue nursing or stop taking the drug, considering the importance to you and your health.

Pentoxifylline leaves the body through the kidneys. Hence, the risk of toxicity may be higher in people with kidney disease. Your healthcare provider may reduce your dose frequency to once daily.

If you miss a dose of this medication, take it as soon as you remember. You can skip the missed dose if it's almost time for your next dose. Resume medication at your next scheduled time. Do not take extra to make up for the missed dose. Call your healthcare provider if you are unsure of what to do. 

Pentoxifylline overdose can happen if you take too much of it. An overdose can cause serious complications, such as:

If you think you or someone else may have overdosed on pentoxifylline, call a healthcare provider or the Poison Control Center (800-222-1222).

If someone collapses or isn't breathing after taking pentoxifylline, call 911 immediately.

It may take several weeks for this medicine to work. If you feel that pentoxifylline is not working, do not stop taking it on your own. Instead, check with your doctor.

Smoking tobacco may worsen your condition since nicotine may further narrow your blood vessels. Therefore, it is best to avoid smoking.

In some cases, your healthcare provider may decide not to prescribe pentoxifylline for you.

This medication may not be best for you if you:

Watch out for these medications when taking pentoxifylline, as they can affect how it works in the body.

Anticoagulants or Platelet Aggregation Inhibitors

Avoid combining pentoxifylline with anticoagulants, which slow down your body's ability to clot blood, and platelet aggregation inhibitors (antiplatelet drugs), which prevent blood cells called platelets from clumping together and forming blood clots, as doing so may cause bleeding.

Taking pentoxifylline with theophylline, a drug used to treat lung diseases such as asthma and chronic obstructive pulmonary disease (COPD), can lead to theophylline toxicity.

The combination of pentoxifylline and ketorolac, a short-term treatment for moderate to severe pain in adults, may increase the risk of bleeding in the gut or other bleeding, which can be life-threatening.

Taking pentoxifylline with the muscle relaxant tizanidine may increase the risk of bleeding in the gut or other bleeding, which can be life-threatening.

The combination of pentoxifylline and antihypertensives (drugs to treat high blood pressure) may increase the risk of bleeding in the gut or other bleeding, which can be life-threatening. Examples of anti-hypertensive drugs are:

The combination of pentoxifylline and caffeine may increase caffeine levels and the risk of toxicity. There is also a higher risk of heart-related effects.

This is not a comprehensive list of medications that may affect how pentoxifylline works or how it may affect other drugs. Tell your healthcare provider or pharmacist about all your current medicines and supplements. Some medicines can increase the risk of severe side effects from pentoxifylline. 

Medications similar to pentoxifylline include:

Cilostazol works differently than pentoxifylline. It relaxes the muscles in the blood vessels that supply blood to the legs to help them dilate. It also prevents platelets in the blood from sticking together and clotting. Avoid cilostazol if you have heart failure, as it can worsen it.

There are some differences between cilostazol and pentoxifylline. For example, it may take up to 12 weeks before your symptoms improve on cilostazol, four weeks longer than with pentoxifylline. Although you generally take pentoxifylline with food, it is recommended to take cilostazol on an empty stomach. Cilostazol may also be a better option for people with kidney disease as it does not require any dosage adjustment. 

Aspirin works differently than pentoxifylline. It prevents blood clots from forming and narrowing the arteries even further. Possible side effects include bleeding or an allergic reaction. Using aspirin in a child or teenager with a fever, flu symptoms, or chickenpox can cause a severe condition called Reye's syndrome. 

Antiplatelet medicines, like clopidogrel, prevent blood clots from forming and narrowing the arteries even further. However, it may not work well if you have genetic factors that affect the breakdown of this drug in your body. Plavix tablets may be a better option for people who have trouble swallowing because they can be crushed, unlike pentoxifylline tablets. It is also a safer choice in pregnancy.

This is a list of drugs that are similar to pentoxifylline. It is not a list of medicines recommended to take with pentoxifylline. You should not take these drugs together. Ask your pharmacist or a healthcare provider if you have questions.

Pentoxifylline improves blood flow by decreasing its viscosity. In people with intermittent claudication, pentoxifylline increases in blood flow to the affected areas with limited circulation and increases tissue oxygen levels.

Because they are extended-release tablets, pentoxifylline tablets should be swallowed whole. You should not crush or chew them. Crushing, chewing, or breaking the tablets will alter how the medication is released.

If your symptoms don’t improve right away, it is recommended to continue treatment for at least eight weeks. You may not see it working until that time frame. Speak to your healthcare provider before stopping any medications.

Pentoxifylline does not cure intermittent claudication. It can only improve its symptoms. It may take up to four weeks before your symptoms improve. Keep using the medicine as directed, and tell your healthcare provider if your symptoms do not improve after eight weeks of treatment. If you have trouble taking this medication, consider setting alarms on your phone or calendar. 

Contact your healthcare provider or pharmacist if you have questions about the medication. 

Verywell Health's drug information is meant for educational purposes only and is not intended to replace medical advice, diagnosis, or treatment from a healthcare provider. Consult your healthcare provider before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

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National Institutes of Health National Heart, Lung, and Blood Institute. What is peripheral artery disease?

DailyMed. Label: Pentoxifylline tablet, extended release.

Thursz MR, Richardson P, Allison M, et al. Prednisolone or pentoxifylline for alcoholic hepatitis. N Engl J Med. 2015;372(17):1619-28. doi:10.1056/NEJMoa1412278

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