Selegiline: Formula, Presentation, Indications, Action Mechanism, Dosage, Side Effects and Interactions

This drug selectively inhibits monoamine oxidase B, preventing the breakdown of a chemical called dopamine in the brain.

The low levels present in the brain of this substance are intimately associated with Parkinson’s disease.

Selegiline is used together with other medications such as levodopa and carbidopa to treat the symptoms of Parkinson’s disease.

Chemical formula

  • C13H17N.


Its presentation in the market is in tablets or capsules of 1.25 and 5 mg of selegiline hydrochloride.


This medication is used to treat movement disorders caused by Parkinson’s disease.

It does not cure Parkinson’s disease, but it can improve tremors, muscle stiffness, loss of normal movement as the dose of other drugs for Parkinson’s disappears (failure at the end of the amount), and sudden change between normal movement and stiffness.

You can improve your range of motion and the ability to walk, dress, and exercise.


Mechanism of action

Selegiline acts as an enzyme blocker and works by slowing the breakdown of certain natural substances, which behave as neurotransmitters in the brain, such as dopamine, norepinephrine, and serotonin.


For the treatment of Parkinson’s disease:

An initial dose of 5 mg orally is recommended at breakfast and 5 mg at lunch, 10 mg per day.

After 2 to 3 days of therapy with selegiline, you can begin to decrease the dose by administering together with the levodopa in 10 to 30% as tolerated by the patient, then continue to fall depending on the response of the patient.

The dose should never exceed 10 mg a day. Foods or liquids should not be taken for 5 minutes after the amount.

The doctor should adjust the doses in renal failure and hepatic impairment cases since their safety and efficacy are not established.

This medication is taken orally, usually twice a day, with breakfast and lunch.

Taking selegiline later in the day can cause problems sleeping.

The dose is based on the medical condition and the response to the patient’s therapy.

The dose should not be increased or taken more frequently than indicated.

It may take a few weeks until all the benefits of the medication are noticed.

The doctor should be consulted before stopping treatment and in cases where the medication does not work or if the patient’s condition worsens.

Side effects

The administration of selegiline can cause severe side reactions, such as:

  • Fainting.
  • Loss of balance
  • Mental and mood changes include agitation, confusion, depression, and hallucinations.
  • Unusual impulses such as the increased need to participate in games of chance.
  • Changes in sexual capacity and an increase in sexual needs.
  • The worsening of stiffness and spasms.
  • Tremors
  • Swollen legs and ankles.
  • Difficulty urinating.
  • Unusual weight gain
  • The easy onset of bleeding and bruising.
  • Stools are black or tarry, black vomit with the appearance of ground coffee.
  • Dizziness
  • Abdominal pain.
  • Dry mouth.
  • Sickness.
  • Stomach ache.
  • Difficulty sleeping and headache.

If you are also taking the medication together with levodopa, you may have symptoms such as tremors, muscle stiffness, mental and mood changes, hallucinations, and abnormal dreams.

This medication can rarely cause an extremely high blood pressure attack, such as a hypertensive crisis, which can be fatal.

Many drug-food interactions can increase the risk of serious adverse reactions such as frequent severe headaches and fast, slow or irregular heartbeat.

Intense pain in the chest, presence of stiffness and pain in the neck, intense nausea and vomiting, excessive sweating and cold and clammy skin, sometimes with the appearance of fever, dilated pupils, changes in vision such as double and blurred vision, sensitivity to light (photophobia), among others.

This medication can increase serotonin levels and rarely causes a serious condition called serotonin syndrome.

This risk increases if you are also taking other medications that increase serotonin, and you should seek immediate medical attention if any of the following symptoms occur:

Hallucinations, unusual restlessness, loss of coordination, fast heartbeat, intense dizziness, unexplained fevers, nausea, vomiting, severe diarrhea, and muscle spasms.

Having a severe allergic reaction to this medication is rare.

However, symptoms of a severe allergic reaction may occur, which may include: Rashes, itching, and swelling, especially of the face, tongue, throat, dizziness, and shortness of breath.

Some people receiving treatment with selegiline have suddenly fallen asleep during their usual daily activities: talking on the phone or driving.

In some cases, sleep occurs without any drowsiness beforehand so that the sleep effect can occur at any time during the selegiline treatment.

Contraindications and warnings

This medication is contraindicated if the patient is allergic to the drug or if they suffer from any other type of allergy.

This product may also contain inactive ingredients, giving rise to allergic reactions and other problems.

In the last five weeks, neither should selegiline be used if the patient has been undergoing treatment with fluoxetine (Prozac, Sarafem, and others).

Before using this medication, the doctor should be informed of the patient’s medical history, especially when certain adrenal gland tumors such as pheochromocytoma are present.

Also, cerebrovascular diseases such as strokes, heart problems such as congestive heart failure, heart attacks, and bleeding problems.

Also, history of severe and frequent headaches, peptic ulcer disease and diabetes, and personal and family history of mental and mood disorders such as schizophrenia and bipolar disorder.

As well as personal and family history of high blood pressure, liver diseases, and overactive thyroid.

This medicine may cause side effects such as dizziness or drowsiness.

If an increase in sleepiness is experienced or the patient tends to fall asleep during the day, they should not drive or participate in any activity that requires alertness.

This risk of its effect on alertness and sleep increases with alcohol or interaction with other medications.

To minimize the effects of dizziness and the risk of fainting, the patient should get up slowly when in a sitting or lying position.

If the patient is going to undergo some surgery, the doctor or dentist treated with this medication should be informed.

You may need to stop taking this medicine before the intervention.

Selegiline should be used during pregnancy only when necessary and when the doctor evaluates the beneficial relationship between the mother and the fetus.

Because there is no research to determine if this medication passes through breast milk, you should consult your doctor before breastfeeding.


Interactions with other medications can change the functioning of drugs or increase the risk of severe side effects.

Some products that may interact with selegiline include:

  • Antidepressants include bupropion, maprotiline, and mirtazapine.
  • Other monoamine oxidase inhibitors include isocarboxazid, linezolid, methylene blue, moclobemide, phenelzine, procarbazine, rasagiline, and safinamide, tranylcypromine.
  • Appetite suppressants such as diethylpropion.
  • Attention, deficit disorder medications, include atomoxetine, methylphenidate, apraclonidine, buspirone, carbamazepineoxcarbazepinecyclobenzaprine, and deutetrabenazine.
  • Certain herbal products such as ephedrine from the sea.
  • Cold medicines or nasal decongestants include phenylephrine, phenylpropanolamine, pseudoephedrine, and fentanyl.
  • Illegal drugs like LSD and phenylethylamines.
  • Stimulants such as amphetamines and ephedrine.
  • Supplements such as tryptophan, tyramine, and tetrabenazine.
  • Certain “triptans” treat migraine headaches, such as rizatriptan, sumatriptan, zolmitriptan, and valentine.

Before taking any of these medications, you must wait at least 14 days after stopping treatment with selegiline.

The risk of serotonin syndrome and toxicity increases if you take other medications that increase serotonin.

The risk of serotonin syndrome and toxicity may be more likely when starting or increasing the dose of these medications.

The doctor should be informed if fluoxetine has been taken for at least five weeks before you start taking selegiline.

To avoid a severe reaction to blood pressure, it is essential to follow a special diet recommended by the nutritionist to limit the intake of tyramine while taking this medication.

Avoid high-tyramine foods and beverages, including:

  • Cured cheeses such as blue cheese, cheddar cheese, and parmesan cheese.
  • Dried, aged, or fermented meats and sausages such as salami and sausage.
  • Canned fish, such as pickled herring.
  • Products containing large amounts of yeast include concentrated yeast extract, broth cubes, dehydrated soups, and powdered sauce.
  • Homemade bread or fermented dough, fermented foods such as sauerkraut, kimchi.
  • Most soy products, red wine, sherry, draft beers, and vermouth.

Limit or avoid moderate tyramine foods, including avocados, bananas, aubergines, green beans, raisins, raspberries, red plums, spinach, tomatoes, and chocolate.

Dairy products with dairy crops such as buttermilk, yogurt, sour cream, fish eggs, pâté, peanuts, coffee, cola, non-alcoholic beer, bottled beer, distilled spirits, and White wine.

This medicine may interfere with specific medical laboratory tests, including a brain scan to detect Parkinson’s disease, causing false results.