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.
Abnormal heart rhythms: This medication can cause abnormal heart rhythms. Certain medications (e.g., sotalol, quinidine, thioridazine, chlorpromazine, droperidol, pimozide, moxifloxacin, mefloquine, pentamidine, arsenic trioxide, probucol, tacrolimus) can increase the risk of a type of abnormal heart rhythm called QT prolongation, and should not be used in combination with methotrimeprazine. You are more at risk for this type of abnormal heart rhythm and its complications if you:
- are female
- are older than 65 years of age
- have a family history of sudden cardiac death
- have a history of heart disease or abnormal heart rhythms
- have a slow heart rate
- have congenital prolongation of the QT interval
- have diabetes
- have had a stroke
- have low potassium, magnesium, or calcium levels
- have nutritional deficiencies
If you have heart disease and abnormal heart rhythms, or are taking certain medications (e.g., verapamil, atazanavir), 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.
Blood clots: Rarely, this medication may increase the chance of blood clot formation, causing reduction of blood flow to organs or the extremities. If you have a history of clotting you may be at increased risk of experiencing blood clot-related problems such as heart attack, stroke, or clots in the deep veins of your leg. 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.
If you experience symptoms such as sharp pain and swelling in the leg, difficulty breathing, chest pain, blurred vision, or difficulty speaking, contact your doctor immediately.
Body temperature: Methotrimeprazine, like other antipsychotic medications, may interfere with your body's ability to regulate body temperature. People who exercise vigorously, who are exposed to extreme heat, are dehydrated, or are taking anticholinergic medications (e.g., benztropine, oxybutynin) are more at risk. Contact your doctor as soon as possible if you feel very hot and are unable to cool.
Take care to avoid overheating during strenuous exercise or in hot temperatures, and avoid becoming dehydrated by drinking enough fluids.
Diabetes: Methotrimeprazine may increase blood sugar for people with diabetes or those who are at risk for diabetes. If you have diabetes, monitor your blood sugar frequently as recommended by your doctor. If you experience symptoms of high blood sugar (e.g., increased urination, increased thirst, increased eating, and weakness) while taking this medication, contact your doctor.
Dizziness/lightheadedness: In high doses, dizziness or lightheadedness when getting up from a sitting or lying position may be experienced at the start of treatment. To reduce the possibility of experiencing this, rise slowly from a sitting or lying position.
Drowsiness/reduced alertness: Methotrimeprazine can cause drowsiness and reduced alertness, especially during the first few days of treatment. Avoid driving, operating machinery, or performing other tasks that require mental alertness until you have determined how this medication affects you.
Medical conditions: If you have arteriosclerosis, heart problems, glaucoma, or prostate problems, 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.
Neuroleptic malignant syndrome (NMS): This medication may cause a potentially fatal reaction called neuroleptic malignant syndrome (NMS). If you develop symptoms of NMS, such as muscle stiffness, fever, confusion, sweating, or irregular heartbeat, stop taking this medication and seek immediate medical attention.
Tardive dyskinesia: People taking this medication may develop tardive dyskinesia, a syndrome of uncontrolled body movements. This syndrome may be irreversible. If you develop uncontrolled or unusual body movements, contact your doctor as soon as possible.
Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. Infants born to mothers who used methotrimeprazine in the later part of pregnancy have had abnormal muscle movement and withdrawal symptoms, including decreased muscle tone, sleepiness, difficulty feeding and severe difficulty breathing after birth. These symptoms can be severe and need medical attention. If you become pregnant while taking this medication, contact your doctor immediately.
Breast-feeding: Methotrimeprazine 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.
Seniors: Seniors with dementia who take this medication may be at an increased risk of death due either heart disease or infections compared to seniors who are not taking this medication. The use of methotrimeprazine by older adults is not recommended.