Magnacet Side Effects

Shionogi, Inc. manufactures Magnacet in various strengths, containing 5 mg, 7.5 mg or 10 mg of oxycodone and 400 mg of acetaminophen.

Doctors prescribe Magnacet to relieve a patient's moderate to severe pain. Recreational users target Magnacet because of the euphoric feeling oxycodone provides.

Oxycodone is a semi-synthetic opioid pain reliever. Pharmacologists create oxycodone from thebaine extracted from the opium poppy plant, Papaver somniferum. Oxycodone works to relieve pain by binding to receptors in the nervous system and messages of pleasure to the brain. As the result, many side effects associated with Magnacet affect the nervous system.

Oxycodone also acts on the breathing centers of the brain to soothe a cough. Because of this Magnacet may cause respiratory depression and other serious breathing problems.

Opioids including oxycodone work on smooth muscle groups like those found in the digestive tract; Magnacet may cause digestive issues including constipation.

Acetaminophen is a mild pain reliever that also reduces fever and inflammation. Acetaminophen blocks the production of prostaglandin, a natural substance that sends messages of pain to the brain, triggers swelling and tells the brain to increase body temperature. Most consumers tolerate acetaminophen well.

Side Effect Information

Magnacet, like any medication, can cause side effects. Many people experience no, or minor, side effects while taking Magnacet. Most side effects associated with Magnacet are not serious and go away after a few days of use at therapeutic doses. A few side effects are serious, requiring immediate medical attention.

Magnacet side effects are typical of any opioid. Taking large doses or using Magnacet for a long time increases the risk for adverse reactions.

Abuse and Physical Dependence

One side effect is the potential for abuse, physical dependence or addiction. The U.S. Drug Enforcement Agency, or DEA, classifies substances according to the potential for abuse. The DEA classifies all medications including oxycodone, including Magnacet, as a Schedule II narcotic. This means Magnacet has the same relative risk for abuse as OxyContin or raw opium.

Using Magnacet continuously for a few weeks may cause the consumer to become opioid-dependent. An opioid-dependent person suffers flu-like withdrawal symptoms when he stops taking Magnacet. Some medications, including naloxone, will reduce oxycodone levels and cause withdrawal symptoms in an opioid-dependent person.

Withdrawal symptoms appear in two waves, and last five or more days with the worst symptoms appearing on or about the fourth day.

Early symptoms of withdrawal include:

  • Agitation
  • Anxiety
  • Muscle aches
  • Increased tearing
  • Insomnia
  • Runny nose
  • Sweating
  • Yawning

Late symptoms of withdrawal include:

  • Abdominal cramping
  • Diarrhea
  • Dilated pupils
  • Goose bumps
  • Nausea
  • Vomiting

To avoid withdrawal symptoms, someone who has taken Magnacet for more than a few weeks should wean himself from this medication by taking successively smaller doses further apart. A qualified detoxification facility can help a person whose withdrawal symptoms prevent him from quitting Magnacet.

Magnacet Addiction

It is possible to become addicted to Magnacet. An addicted person will crave oxycodone and engage in drug-seeking behaviors when he runs out of Magnacet. Magnacet addiction requires professional rehabilitative care; without adequate treatment, Magnacet addiction can cause disability or premature death.


Continuous Magnacet use may increase tolerance. High tolerance means someone has to take stronger doses of Magnacet to achieve the same analgesic or euphoric effects. Taking higher doses or using Magnacet more often may raise the risk for side effects or increase their severity.

Discontinuing Magnacet for even a short time may lower tolerance, meaning the individual is more sensitive to the effects of Magnacet. As a result, someone can potentially overdose on a smaller amount of Magnacet than he used to take before experiencing even moderate withdrawal symptoms.

Most Frequently Observed Side Effects

The most frequently reported adverse reactions include reactions include lightheadedness, dizziness, drowsiness or sedation, nausea, and vomiting. These side effects are more prominent in ambulatory patients than for those confined to a bed or wheelchair. Lying down reduces these symptoms for most sufferers.

Allergic Reaction

Patients who are allergic to oxycodone, acetaminophen or other opioids or pain relievers should not take Magnacet.

Anyone can suffer an allergic reaction to Magnacet. An allergic reaction is a serious medical emergency that requires immediate care. Bring the bottle Magnacet along with the rest of the medications to help the doctors determine the cause of the reaction.
Common symptoms of a mild allergic reaction include:

  • Hives, especially over the neck and face
  • Itching
  • Nasal congestion
  • Rashes
  • Watery, red eyes

Symptoms of a moderate to severe reaction include:

  • Abdominal pain
  • Abnormal or high-pitched breathing sound
  • Anxiety
  • Chest discomfort or tightness
  • Cough
  • Diarrhea
  • Difficulty breathing
  • Difficulty swallowing
  • Dizziness or light-headedness
  • Flushing or redness of the face
  • Nausea or vomiting
  • Palpitations
  • Swelling of the face, eyes or tongue
  • Unconsciousness
  • Wheezing

Anaphylaxis is a serious, potentially deadly form of an allergic reaction. Anaphylaxis usually starts within seconds or minutes of exposure, but anaphylaxis may start as late as a half an hour or longer after the victim consumes Magnacet. Transport any cases of suspected anaphylaxis to the nearest hospital immediately.

Symptoms of anaphylaxis include:

  • Abdominal pain
  • Abnormal, high-pitched breathing sounds
  • Anxiety
  • Chest discomfort or tightness
  • Cough
  • Diarrhea
  • Difficulty breathing
  • Difficulty swallowing
  • Dizziness or light-headedness
  • Hives, itchiness
  • Nasal congestion
  • Nausea or vomiting
  • Palpitations
  • Skin redness
  • Slurred speech
  • Swelling of the face, eyes, or tongue
  • Unconsciousness
  • Wheezing

Signs include:

  • Abnormal heart rhythm
  • Blue skin from lack of oxygen
  • Fluid in the lungs
  • Hives
  • Low blood pressure
  • Mental confusion
  • Pale skin from shock
  • Rapid pulse
  • Swelling in the throat
  • Swelling of the eyes or face
  • Weakness
  • Wheezing


Some people are hypersensitive to the effects of Magnacet. Hypersensitivity may cause skin reactions such as skin eruptions, hives and redness. Hypersensitivity may also cause blood reactions, including low platelet counts that could lead to clotting problems along with low white blood cell and red blood cell counts.

Serious Magnacet Side Effects

The most serious side effects associated with Magnacet use include respiratory depression, apnea, respiratory arrest, circulatory depression, hypotension, and shock. Respiratory depression is a condition where the lungs do not exchange oxygen and carbon dioxide well, causing a lack of oxygen and build-up of toxic gases. Symptoms of respiratory depression include slow, shallow or irregular breathing and a bluish tint around the eyes, mouth and fingertips.

By body system

Body as a Whole

Magnacet may cause an anaphylactic or allergic reaction. It can also cause general malaise, fatigue and weakness. Magnacet consumers may experience fever, chest pain, thirst headache, increased sweating and low body temperature. Accidental overdose or non-accidental overdose may occur.


Magnacet side effect may affect the heart and circulatory system, causing high blood pressure, low blood pressure or blood pressure that changes when the consumer sits or stands. Magnacet may also be associated with slow or irregular heartbeats.

Central and Peripheral Nervous System

Magnacet may depress the nervous system and cause stupor, confusion or lethargy, or it may stimulate the nervous system to cause anxiety, tremors, agitation or dizziness. Magnacet consumption may cause mental impairment, seizures or swelling of the brain. Consumers may experience a prickling or numb feeling or lose sensitivity.

Fluid and Electrolyte

Magnacet use may cause fluid and electrolyte imbalances such as dehydration, high potassium levels, too much acid in the blood or low levels of carbon dioxide in the blood.


Magnacet may cause upset stomach, taste disturbances, abdominal pain, bloating and sweating. It may also cause diarrhea, dry mouth, gas, nausea or vomiting. Rarely, patients have experienced pancreatitis or serious intestinal problems such as obstruction after using Magnacet.


Magnacet use may cause liver problems such as altering enzyme levels, hepatitis, liver failure, a yellowing of the skin or eyes and other types of serious liver problems.


Magnacet consumers have reported hearing loss or ringing in the ears after using this medication.


Magnacet use may decrease platelet counts, increasing the risk for the development of serious clotting problems.


Some patients are hypersensitive to the effects of Magnacet and may experience acute anaphylaxis, rapid swelling under the skin, asthma, breathing problems, swelling of the throat and hives.

Metabolic and Nutritional

Magnacet use may cause metabolic disturbances including fluctuations in blood sugar levels. This medication may also cause imbalances in the body's acid and base levels.


Patients taking Magnacet may experience muscle aches. Consumers may rarely experience a serious loss of muscle fiber, a condition known as rhabdomyolysis.


Magnacet use may cause visual disturbances, pinpoint pupils or red dyes.


As with other drugs containing oxycodone or other opioids, Magnacet use is associated with a relatively high risk for drug abuse that may lead to physical dependence or psychiatric addiction. Other psychiatric adverse effects of Magnacet include insomnia, confusion, anxiety, agitation and depressed level of consciousness. Some Magnacet consumers report nervousness, hallucination, somnolence, depression or thoughts of suicide.

Respiratory System

Magnacet use may cause breathing problems including bronchospasm, shortness of breath, abnormally deep breathing or slow or rapid breathing. Magnacet may cause fluid in the lung or swelling of the throat.

Skin and Appendages

Magnacet use may cause adverse reactions involving the skin, resulting in redness, hives, rash or flushing of the skin.


Magnacet side effects may cause the serious kidney and urinary problems, interstitial nephritis and papillary necrosis. Other side effects include an excessive amount of protein in the urine, poor kidney function and kidney failure. Magnacet may cause urinary retention, a condition characterized by poor urine output.