Mega-Trim Side Effects

Generic name: phenylpropanolamine

Note: This document contains side effect information about phenylpropanolamine. Some dosage forms listed on this page may not apply to the brand name Mega-Trim.

Applies to phenylpropanolamine: oral capsule extended release, oral tablet, oral tablet extended release.

If you experience any of the following serious side effects from this medication, stop taking phenylpropanolamine (the active ingredient contained in Mega-Trim) and seek emergency medical attention:

• an allergic reaction (difficulty breathing; closing of your throat; swelling of your lips, tongue, or face; or hives);

• seizures;

• unusual behavior or hallucinations; or

• an irregular or fast heartbeat.

Other, less serious side effects may be more likely to occur. Continue to take phenylpropanolamine and talk to your doctor if you experience

• dizziness, lightheadedness, or drowsiness;

• headache;

• insomnia;

• anxiety;

• tremor (shaking) or restlessness;

• nausea or vomiting; or

• sweating.

Side effects other than those listed here may also occur. Talk to your doctor about any side effect that seems unusual or that is especially bothersome.

For Healthcare Professionals

Applies to phenylpropanolamine: oral capsule extended release, oral tablet, oral tablet extended release.

Cardiovascular

Cardiovascular adverse effects may be associated with phenylpropanolamine (the active ingredient contained in Mega-Trim) Phenylpropanolamine can cause a significant rise in heart rate. Hypertension and arrhythmias may be problematic in susceptible patients. Cardiovascular side effects have also included an increased risk of hemorrhagic stroke.^[Ref]

Phenylpropanolamine causes vasoconstriction which usually does not result in blood pressure elevations in healthy adults given normally prescribed dosages. However, phenylpropanolamine administration may be problematic for patients with preexisting hypertension and those receiving higher dosages. In general, 75-mg of sustained-release phenylpropanolamine will not produce a significant increase in blood pressure in normotensive patients, but 150-mg of sustained-release phenylpropanolamine can.

The combination of caffeine and phenylpropanolamine is more apt to cause hypertension. Although caffeine is no longer added to phenylpropanolamine as an anorexiant, this combination is available as "look-alikes" for amphetamines. Hypertensive crisis has occurred occasionally subsequent to overuse, overdose, and ingestion of normally recommended doses. Hypertensive crisis may be accompanied by headache, blurred vision, confusion, intracranial hemorrhage, encephalopathy, or seizures.

Arrhythmias may be produced in predisposed patients. The majority of reports of arrhythmias involve overuse or overdose. Rarely, high doses of phenylpropanolamine may cause chest pain and evidence of myocardial injury.

One study reported that taking phenylpropanolamine increases the risk of hemorrhagic stroke in women. Men may also be at risk. Although the risk of hemorrhagic stoke is very low, the FDA recommends that all use of phenylpropanolamine be discontinued.^[Ref]

Nervous system

Seizures may occur in rare cases of hypertensive crisis and have been reported with normally recommended doses as well as in cases of overuse or overdose.

There have been anecdotal reports of cerebrovascular hemorrhage largely associated with an uneven pattern of cerebrovascular spasm referred to as vascular beading. Vascular beading has also been reported in the absence of hemorrhage. Intracranial hemorrhage has almost always been associated with hypertension.^[Ref]

Phenylpropanolamine produces nervous system stimulation, resulting in tremor, anxiety, insomnia, dizziness, and nervousness. Headache may also occur.^[Ref]

Psychiatric

Psychiatric reactions occur infrequently but include acute mania, anxiety, paranoia, confusion, agitation, and hallucinations. These reactions may be more common in women.^[Ref]

Psychotic reactions to phenylpropanolamine have occurred in patients receiving normally recommended doses and in cases of abuse. In a few patients, phenylpropanolamine appears to have exacerbated an underlying bipolar disorder which was previously undiagnosed.

A psychotic episode consisting of abnormal behavior was reported in a young woman following a week of therapy with Naldecon (phenylephrine, phenylpropanolamine, chlorpheniramine, and phenyltoloxamine) and amantadine. The patient had no personal or family history of psychiatric illness and no history of recreational substance use. It is uncertain whether the episode was due to the amantadine, the phenylpropanolamine, or another component in the Naldecon, or if it was an interaction between the drugs.^[Ref]

Gastrointestinal

Gastrointestinal adverse effects most commonly seen are anorexia and gastric irritation. Nausea and vomiting have occurred in conjunction with hypertensive episodes.^[Ref]

Hypersensitivity

Hypersensitivity reactions to phenylpropanolamine (the active ingredient contained in Mega-Trim) may occur.^[Ref]

Renal

Rarely, phenylpropanolamine (the active ingredient contained in Mega-Trim) may cause acute interstitial nephritis.^[Ref]

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.

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