Selegiline belongs to the class of medications called monoamine oxidase inhibitors (MAOIs). It is used to treat Parkinson's disease. It acts on the nervous system to increase the levels of a chemical called dopamine. Low dopamine levels in the brain are responsible for many of the symptoms of Parkinson's disease, so this medication works by rebalancing the levels of dopamine.

This medication may be taken alone or in combination with levodopa to treat the symptoms of Parkinson's disease.

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 recommended adult dose of selegiline is 5 mg taken twice a day with breakfast and lunch.

Do not take this medication later in the day because it may interfere with sleep. Do not use doses higher than this, as there is increased risk of side effects at higher doses and no evidence that there is any greater effect of the medication.

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 given 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 of this medication, take it as soon as possible. If you do not remember your dose until late afternoon or evening, skip the missed dose and continue with your regular 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 keep it out of the reach of children.

Do not take selegiline if you:

• are allergic to selegiline or to any of the ingredients of the medication
• are taking the medication called meperidine (and possibly other narcotic pain relievers, such as tramadol or methadone)
• have active peptic ulcers
• have a problem such as excessive tremor or involuntary movements of the muscles of the face
• have severe psychosis or severe dementia

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.

• abdominal or stomach pain
• anxiety
• back or leg pain
• blurred or double vision
• body ache
• burning of lips, mouth, or throat
• chills
• constipation
• decreased sexual ability
• diarrhea
• dizziness or lightheadedness, especially when rising from a lying or sitting position
• drowsiness
• dry mouth
• feeling faint
• headache
• high or low blood pressure
• inability to move
• increased sensitivity of skin to light
• increased sweating
• irritability (temporary)
• loss of appetite
• memory problems
• mood changes
• muscle pain
• nausea
• nervousness
• numbness of fingers or toes
• pounding or fast heartbeat
• ringing or buzzing in ears
• slowed movements
• taste changes
• trouble sleeping
• unusual feeling of well-being
• unusual tiredness or weakness
• unusual weight loss
• urination changes (e.g., increased need to urinate at night, slow, difficult or frequent urination)
• vivid dreams
• 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:

• difficulty breathing (e.g., tightness in chest, wheezing)
• confusion
• hallucinations (hearing, seeing, or feeling things that aren't actually there)
• increase in unusual movements of body (e.g., twisting movements of body; uncontrolled chewing movements; uncontrolled movements of face, neck, back, arms, or legs)
• irregular heartbeat
• lip smacking or puckering
• loss of balance control
• puffing of cheeks
• rapid or worm-like movements of tongue
• restlessness or desire to keep moving
• signs of bleeding disorder (bloody or black, tarry stools, vomiting of blood or material that looks like coffee grounds, blood in urine)
• signs of depression (loss of interest in activities, sleeping too much, difficulty sleeping, eating more or less than usual, difficulty concentrating)
• swelling of feet or lower legs

Get medical help immediately if any of the following signs of extremely high blood pressure occur (caused by the use of this medication with certain foods or medications):

• chest pain (severe)
• enlarged pupils
• fast or slow heartbeat
• headache (severe)
• increased sensitivity of eyes to light
• increased sweating (possibly with fever or cold, clammy skin)
• nausea and vomiting (severe)
• stiff or sore neck

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

• chest pain
• convulsions (seizures)
• difficulty opening mouth, or lockjaw
• difficulty breathing (e.g., tightness in chest, wheezing)
• dizziness (severe) or fainting
• fast or irregular pulse (continuing)
• high fever
• high or low blood pressure
• increased sweating (possibly with fever or cold, clammy skin)
• severe headache
• severe spasm where the head and heels are bent backward and the body is arched forward
• shortness of breath, wheezing, difficult breathing
• signs of a severe allergic reaction (e.g., hives; difficulty breathing; or swelling of the mouth, lips, tongue, or throat; peeling, blistering skin)

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.

Antidepressant medication: Severe reactions are possible when selegiline is combined with tricyclic antidepressants or serotonin reuptake inhibitors, medications used to treat depression. The combination of selegiline and antidepressants from these groups must be avoided. Symptoms of a reaction may include muscle rigidity and spasms, difficulty moving, and changes in mental state including delirium and agitation. Coma and death are also possible.

If you take any of these medications or have taken antidepressants recently, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Headache: If you experiencing a severe headache or other unusual symptoms while taking selegiline, report them to a doctor immediately.

Levodopa: Some people who take selegiline may experience a worsening of levodopa-associated side effects, such as unusual movements of the body. Report these effects to your doctor as soon as possible. Your doctor may help with these effects by reducing the dose of levodopa.

Liver function: People taking selegiline may have changes in liver function that produce abnormal liver test results. Your doctor may recommend regular liver tests while you are taking this medication.

Maximum dose: Do not exceed the recommended daily dose of 10 mg of selegiline.

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: It is not known if selegiline passes into breast milk. If you are a breast-feeding mother and are taking this medication, 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.

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

• alcohol
• aldesleukin
• aliskiren
• alpha agonists (e.g., apraclonidine, clonidine, methyldopa)
• alpha/beta agonists (e.g., epinephrine, norepinephrine)
• alpha blockers (e.g., alfuzosin, doxazosin, tamsulosin)
• amiodarone
• amphetamines (e.g., dextroamphetamine, lisdexamfetamine)
• angiotensin converting enzyme inhibitors (ACEIs; captopril, enalapril, ramipril)
• angiotensin receptor blockers (ARBs; e.g., candesartan, losartan, irbesartan)
• antipsychotics (e.g., aripiprazole, brexpiprazole, chlorpromazine, clozapine, haloperidol, olanzapine, quetiapine, risperidone)
• atomoxetine
• atropine
• barbiturates (e.g., butalbital, phenobarbital)
• beta-adrenergic blockers (e.g., atenolol, propranolol, sotalol)
• beta 2 agonists (e.g., salbutamol, formoterol, terbutaline)
• betahistine
• bezafibrate
• birth control pills
• bortezomib
• brimonidine
• bromocriptine
• bupropion
• buspirone
• calcium channel blockers (e.g., amlodipine, diltiazem, nifedipine, verapamil)
• carbamazepine
• cyclobenzaprine
• dextromethorphan
• diabetes medications (e.g., acarbose, canagliflozin, glyburide, insulin, linagliptin, lixisenatide, metformin, repaglinide, rosiglitazone)
• diazoxide
• diphenoxylate
• disopyramide
• diuretics (water pills; e.g., eplerenone, furosemide, hydrochlorothiazide, triamterene)
• domperidone
• ergot alkaloids (e.g., dihydroergotamine)
• esketamine
• guanfacine
• hydralazine
• hydroxychloroquine
• lanreotide
• levodopa
• linezolid
• lithium
• mecasermin
• methadone
• methylphenidate
• metoclopramide
• mifepristone
• minoxidil
• mirtazapine
• monoamine oxidase inhibitors (MAOIs; e.g., moclobemide, phenelzine, rasagiline, safinamide, tranylcypromine)
• nabilone
• narcotic pain relievers (e.g., codeine, fentanyl, morphine, oxycodone)
• nevirapine
• nitrates (e.g., nitroglycerin, isosorbide dinitrate, isosorbide mononitrate)
• obinutuzumab
• octreotide
• oxcarbazepine
• pasireotide
• pentamidine
• pentoxifylline
• phosphodiesterase 5 inhibitors (e.g., sildenafil, tadalafil, vardenafil)
• pizotifen
• pramipexole
• primidone
• quinine
• riociguat
• ropinirole
• rotigotine
• sacubitril
• St. John's wort
• selective serotonin reuptake inhibitors (SSRIs; e.g., fluoxetine, fluvoxamine, paroxetine, sertraline)
• serotonin antagonists (anti-emetic medications; e.g., granisetron, ondansetron, palonosetron)
• serotonin-norepinephrine reuptake inhibitors (SNRI antidepressants; e.g., venlafaxine)
• solriamfetol
• somatostatin
• sulfonamide antibiotics ('sulfas'; e.g., sulfamethoxazole)
• sunitinib
• terbutaline
• tetrabenazine
• tizanidine
• trazodone
• tretinoin
• tricyclic antidepressants (e.g., amitriptyline, doxepin, nortriptyline)
• Tryptophan
• vilazodone

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 the ones listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications that 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.