Mepergan Fortis Side Effects
Generic name: meperidine / promethazine
Medically reviewed by Drugs.com. Last updated on May 25, 2022.
Note: This document contains side effect information about meperidine / promethazine. Some dosage forms listed on this page may not apply to the brand name Mepergan Fortis.
Applies to meperidine / promethazine: oral capsule.
- This drug is a strong pain drug that can put you at risk for addiction, abuse, and misuse. Misuse or abuse of this drug can lead to overdose and death. Talk with your doctor.
- Do not give this drug to a child younger than 2 years of age. It may cause very bad and sometimes deadly breathing problems.
- Use with care in children 2 years of age and older. Talk with the doctor.
- You will be watched closely to make sure you do not misuse, abuse, or become addicted to this drug.
- This drug may cause very bad and sometimes deadly breathing problems. Call your doctor right away if you have slow, shallow, or trouble breathing.
- The chance of very bad and sometimes deadly breathing problems may be greater when you first start this drug or anytime your dose is raised.
- Even one dose of this drug may be deadly if it is taken by someone else or by accident, especially in children. If this drug is taken by someone else or by accident, get medical help right away.
- Keep all drugs in a safe place. Keep all drugs out of the reach of children and pets.
- Using this drug for a long time during pregnancy may lead to withdrawal in the newborn baby. This can be life-threatening. Talk with the doctor.
- This drug has an opioid drug in it. Severe side effects have happened when opioid drugs were used with benzodiazepines or other drugs that may make you drowsy or slow your actions. This includes slow or troubled breathing and death. Benzodiazepines include drugs like alprazolam, diazepam, and lorazepam. Benzodiazepines may be used to treat many health problems like anxiety, trouble sleeping, or seizures. If you have questions, talk with your doctor.
- Many drugs interact with this drug and can raise the chance of side effects like deadly breathing problems. Talk with your doctor and pharmacist to make sure it is safe to use this drug with all of your drugs.
- Avoid drinking alcohol while taking this drug.
- Get medical help right away if you feel very sleepy, very dizzy, or if you pass out. Caregivers or others need to get medical help right away if the patient does not respond, does not answer or react like normal, or will not wake up.
Serious side effects of Mepergan Fortis
WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:
- Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
- Very bad dizziness or passing out.
- Fast or slow heartbeat.
- A heartbeat that does not feel normal.
- Fever or chills.
- Sore throat.
- Hallucinations (seeing or hearing things that are not there).
- Mood changes.
- Feeling confused.
- Very bad constipation.
- Feeling very sleepy.
- Chest pain.
- Trouble breathing, slow breathing, or shallow breathing.
- Any unexplained bruising or bleeding.
- Change in eyesight.
- Yellow skin or eyes.
- A very bad and sometimes deadly health problem called neuroleptic malignant syndrome (NMS) may happen. Call your doctor right away if you have any fever, muscle cramps or stiffness, dizziness, very bad headache, confusion, change in thinking, fast heartbeat, heartbeat that does not feel normal, or are sweating a lot.
- Some people who take this drug may have muscle movements that cannot be controlled. Call your doctor right away if you have any trouble controlling body movements or if you have muscle problems with your tongue, face, mouth, or jaw like tongue sticking out, puffing cheeks, mouth puckering, or chewing.
- A severe and sometimes deadly problem called serotonin syndrome may happen if you take this drug with certain other drugs. Call your doctor right away if you have agitation; change in balance; confusion; hallucinations; fever; fast or abnormal heartbeat; flushing; muscle twitching or stiffness; seizures; shivering or shaking; sweating a lot; severe diarrhea, upset stomach, or throwing up; or severe headache.
Other side effects of Mepergan Fortis
All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:
- Upset stomach or throwing up.
- Feeling sleepy.
- Dry mouth.
- Sweating a lot.
These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.
You may report side effects to the FDA at 1-800-332-1088. You may also report side effects at https://www.fda.gov/medwatch.
For Healthcare Professionals
The most frequently observed meperidine adverse reactions have included light-headedness, dizziness, sedation, nausea, vomiting, and sweating. Somnolence is the most prominent CNS effect reported with promethazine.[Ref]
Common (1% to 10%): Lightheadedness, dizziness, sedation
Rare (less than 0.1%): Extrapyramidal reactions
Frequency not reported: Weakness, headache, tremor, uncoordinated muscle movements
Common (1% to 10%): Drowsiness
Frequency not reported: Sedation, somnolence, dizziness, confusion, extrapyramidal symptoms, lassitude, tremors, convulsive seizures, neuroleptic malignant syndrome[Ref]
Hyperexcitability and extrapyramidal movements have been reported following a single dose of promethazine.[Ref]
Hyperexcitability and abnormal movements have been reported following a single dose of promethazine.[Ref]
Frequency not reported: Euphoria, dysphoria, agitation, transient hallucinations and disorientation
Frequency not reported: Confusion, disorientation, euphoria, nervousness, insomnia, excitation, catatonic-like states, hysteria, hallucinations, nightmares, agitation, paradoxical reactions, hyperexcitability[Ref]
Frequency not reported: Respiratory depression, respiratory arrest
Common (1% to 10%): Nausea, vomiting
Frequency not reported: Dry mouth, constipation, biliary-tract spasm
Frequency not reported: Tachycardia, bradycardia, increased or decreased blood pressure, faintness[Ref]
Common (1% to 10%): Sweating
Frequency not reported: Facial flushing
Frequency not reported: Visual disturbances
Frequency not reported: Blurred vision, diplopia
More about Mepergan Fortis (meperidine / promethazine)
- Check interactions
- Reviews (5)
- Drug images
- Dosage information
- During pregnancy
- Drug class: narcotic analgesic combinations
Related treatment guides
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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.