Pentoxifylline belongs to the group of medications called vasoactive agents. These medications work by improving blood flow in the arms and legs. Pentoxifylline is used to treat chronic circulation disorders of the arms and legs, such as intermittent claudication (peripheral arterial disease) or ulcers due to poor blood supply. It may allow you to walk further distances before leg pain or cramps occur. It may take up to 2 months to see the full benefits of the medication.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

The usual recommended adult starting dose of pentoxifylline is 400 mg twice daily after meals. Your doctor may adjust the dose over time as needed to a maximum of 400 mg 3 times daily. The tablets must be swallowed whole - do not crush or chew the tablets.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important to take this medication exactly as prescribed by your doctor. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children.

Do not take pentoxifylline if you:

• are allergic to pentoxifylline, to the class of medications called xanthines (e.g., caffeine, theophylline, and theobromine), or to any of the ingredients of the medication
• are having a heart attack
• have severe coronary artery disease and, in the doctor's judgment, stimulation of the heart could prove harmful
• have or have recently had a stomach or intestinal ulcer
• have had recent bleeding in the brain or the eye

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• agitation
• back, leg, or muscle pain
• bloating
• diarrhea
• dizziness or light-headedness
• fever
• flushing
• general feeling of discomfort or feeling unwell
• headache
• heartburn
• increased blood pressure
• nausea
• nosebleeds
• stomach discomfort
• trouble sleeping
• unusual weakness
• vomiting

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• chest pain
• eye problems or vision changes (e.g., blurred vision, blind spots in the vision, itchy and watery eyes)
• fast, pounding, or abnormal heartbeat
• increased frequency of signs of infection (e.g., fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, weight loss, or listlessness)
• irregular heartbeat
• signs of anemia (low red blood cells; e.g., dizziness, pale skin, unusual tiredness or weakness, shortness of breath)
• signs of clotting problems (e.g., unusual nosebleeds, bruising, blood in urine, coughing blood, bleeding gums, cuts that don't stop bleeding)
• signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
• stomach pain or burning
• swelling of the arms, hands, legs, feet and ankles, face
• symptoms of angina (heart muscle not getting enough oxygen; e.g., shoulder, arm, back, throat, jaw or teeth discomfort, chest pain or pressure)
• symptoms of gallbladder inflammation (e.g., fever, nausea, pain spreading to the shoulder or back, severe pain in upper right abdomen)
• trouble breathing, shortness of breath

Stop taking the medication and seek immediate medical attention if any of the following occur:

• chest pain
• difficulty breathing
• seizures
• signs of bleeding in the stomach (e.g., bloody, black, or tarry stools; spitting up of blood; vomiting blood or material that looks like coffee grounds)
• signs of meningitis not caused by infection (e.g., headache (severe), throbbing, or with stiff neck or back)
• symptoms of an allergic reaction, e.g.:
• blisters
• itching
• red spots
• swelling

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Bleeding: The use of pentoxifylline has been associated with bleeding and prolonged clotting time. The risk of bleeding may be increased by combined treatment with blood-thinning medications such as warfarin. Your doctor will monitor you while you are taking pentoxifylline. If you experience any abnormal bleeding (e.g., bleeding around your eyes or blood in your stool), seek immediate medical attention.

Blood pressure: People with low blood pressure may be more sensitive to side effects with the use of this medication. Your doctor will monitor you while you are taking pentoxifylline.

Irregular heartbeat: Pentoxifylline may cause irregular heart rhythms. People with irregular rhythms should discuss with their doctor how this medication may affect their medical condition, how their medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Liver or kidney disease: People with liver or kidney disease should discuss with their doctor how this medication may affect their medical condition, how their medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. Pentoxifylline is not recommended for people with severely reduced kidney or liver function.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: Pentoxifylline passes into breast milk. If you are breast-feeding and are taking pentoxifylline, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using this medication have not been established for children below the age of 18 years.

Seniors: Seniors may be more sensitive to the side effects of this medication. Your doctor will monitor you while you are taking this medication.

There may be an interaction between pentoxifylline and any of the following:

• acetylsalicylic acid (ASA)
• aliskiren
• alpha-agonists (e.g., clonidine, methyldopa)
• alpha-blockers (e.g., alfuzosin, doxazosin, terazosin)
• amiodarone
• angiotensin converting enzyme inhibitors (ACEIs; captopril, enalapril, ramipril)
• angiotensin receptor blockers (ARBs; e.g., candesartan, irbesartan)
• apomorphine
• beta-adrenergic blockers (e.g., atenolol, propranolol, sotalol)
• bromocriptine
• calcium channel blockers (e.g., amlodipine, diltiazem, nifedipine, verapamil)
• diuretics (water pills; e.g., furosemide, hydrochlorothiazide, triamterene)
• cimetidine
• ciprofloxacin
• clopidogrel
• conivaptan
• deferasirox
• dipyridamole
• heparin
• low molecular weight heparins (e.g., dalteparin, enoxaparin, tinzaparin)
• levodopa
• mexiletine
• nabilone
• nitrates (e.g., nitroglycerin, isosorbide dinitrate, isosorbide mononitrate)
• non-steroidal anti-inflammatory medications (NSAIDs; e.g., diclofenac, ibuprofen, ketorolac, naproxen)
• obinutuzumab
• prasugrel
• rasagiline
• riociguat
• ropinirole
• rotigotine
• sacubitril
• selective serotonin reuptake inhibitors (SSRIs; e.g., citalopram, fluoxetine, fluvoxamine, paroxetine, sertraline)
• selegiline
• serotonin-norepinephrine reuptake inhibitors (SNRIs; desvenlafaxine, duloxetine, venlafaxine)
• stiripentol
• tamsulosin
• theophylline
• ticagrelor
• tizanidine
• tricyclic antidepressants (e.g., clomipramine, desipramine, trimipramine)
• vemurafenib
• warfarin

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.