Surmontil (trimipramine), a tricyclic antidepressant, is used to treat depression. It also has some sedative properties. It is said to “brighten up” the dreams because it does not affect the rapid eye movement (REM) phase of sleep.

How Does Surmontil Work?

This drug is a serotonin reuptake inhibitor that also inhibits the reuptake of norepinephrine. The response occurs immediately, however mood improvement may take about two weeks. It is thought that this drug causes changes in receptor sensitivity in the cerebral cortex and hippocampus present in the limbic system. This part of the brain is involved in regulating emotions. Surmontil also suppresses Beta-adrenergic receptors together with serotonin receptors.

History of Surmontil

The U.S. Food and Drug Administration (FDA) approved trimipramine maleate (as Surmontil) oral capsules on January 1, 1982 as a 25 mg and 50 mg capsule. The 100 mg formulation was approved on September 15, 1982. The FDA then approved the generic version of all three formulations on August 2, 2006.


This drug is a dibenzazepine derivative of tricyclic antidepressants. It has both antihistaminic and sedative properties. Surmontil has a molecular formula of C20H26N2 and an average mass of 294.434 Da.

Dosage FAQs

  • What is a normal dose of this medication?
    • Depression: Surmontil is used primarily for depression. For outpatient treatment, individuals are given an initial dose of 75 mg per day, in divided doses or as a single dose at bedtime, which can be increased to 150 mg per day. Dosages over 200 mg per day are not recommended. Maintenance doses can range between 50 mg to 150 mg per day. For inpatient treatment, overall dosage will likely be increased. 100 mg per day in divided doses or a single dose at bedtime can be given initially. The dose can be increased, gradually, to 200 mg per day, depending upon individual response and tolerance. If improvement does not occur in two to three weeks, the dose may be increased to a maximum of 250 mg to 300 mg per day.
  • Does dosage change for geriatric or pediatric individuals?
    • Geriatric: An Initial dose of 50 mg per day in divided doses or at bedtime can be given. This may be increased gradually to 100 mg per day depending on individual response and tolerance.
    • Pediatric: For children above the age of 12, an initial dose of 50 mg per day in divided doses or at bedtime may be given. The total dosage can be increased gradually to 100 mg per day depending on individual response and tolerance.
  • Is it safe to use this drug if I am pregnant or become pregnant during treatment?
    The FDA categorizes this drug in pregnancy category C, which means some animal studies have shown adverse effects on the fetus. There are no significant bodies of research on its effect on human pregnancy, or if this drug can be excreted into breast milk. All benefits should be thoroughly weighed against potential risks before prescribing this drug during pregnancy or continuing treatment if a person become pregnant.
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    Are there ways to get more out of my treatment with this drug?
    This medication is primarily prescribed to treat depression, which is a condition also effectively treated with psychotherapy in many cases. Medication can be great for dulling or removing debilitating side effects, but it does not help a person work toward a long-lasting mental health outcome. If you are prescribed this drug for depression, consider finding a therapist or counselor to help address some of the underlying emotional or behavioral issues associated depression. A therapist can help you better understand your experiences, work with you to develop a healthy self-care routine, and point you toward exercises or activities that may improve your symptoms of depression.
  • How does my body process this drug?
    Surmontil is well-absorbed in the gastrointestinal tract and undergoes liver metabolism. It reaches its peak plasma concentration in about two hours and has a half-life of 16 to 40 hours. This medication is excreted via urine. In the blood, it has a 95% plasma protein binding and has a 17–48L/kg volume of distribution. It has a moderate bioavailability of 18% to 63%.

Possible Side Effects

Surmontil shares many of the side effects typical of tricyclic antidepressants. They include, but are not limited to, the following:

  • Feeling dizzy or faint
  • Dry mouth    
  • Constipation
  • Sweating
  • Feeling anxious or confused
  • Tingling or numb feelings
  • Breast tenderness
  • Difficulties with sexual function
  • Increased appetite and weight
  • Difficulty urinating
  • Tachycardia (rapid heart rate)

Inform your doctor if you experience any of these symptoms. Your dosage may need altered or an alternative medication may be considered.

Drug Interactions

This medication has several significant drug interactions of which to be aware, including:

  • Anticholinergic agents (atropine and belladonna alkaloids): Surmontil produces its own anticholinergic activity, such as urinary retention, angle-closure glaucoma, untreated intraocular hypertension, or uncontrolled primary open-angle glaucoma. Additionally, it may cause gastrointestinal obstructive disorders. Surmontil administered with other anticholinergic agents can exacerbate these effects.
  • Drugs for high blood pressure: This medication can cause the effects of antihypertensive drugs to decrease.   
  • Cimetidine, haloperidol: These drugs are inhibitors of liver enzymes and may reduce the metabolism of Surmontil.
  • Monoamine oxidase inhibitors (MAOIs): These may cause a serious and fatal drug interaction if combined with Surmontil. MAOIs should be avoided for two weeks after discontinuation of the therapy with this medication.
  • Selective serotonin reuptake inhibitors (SSRIs) and serotonin and norepinephrine reuptake inhibitors (SNRIs): SSRIs and SNRIs used in conjunction with this medication may cause serotonin syndrome. This serious condition includes symptoms such as:
    • Confusion
    • Agitation or restlessness
    • Dilated pupils
    • Headache
    • Increase or decrease in blood pressure
    • Increase or decrease in temperature
    • Nausea, vomiting, and diarrhea
    • Increased heart rate
    • Tremor
    • Twitching of muscles
    • Shivering
    • Heavy sweating      
  • Isoniazid, Phenothiazines, Thioridazine, and Theophylline: These drugs, when taken with Surmontil, may cause increased incidence of seizures.
  • Antihistamines: This medication can cause excessive drowsiness if taken with sedating antihistamine.
  • Anti-seizure drugs: This medication can interact with this category of drugs and may lower the seizure threshold and cause more frequent seizures.
  • Anxiolytics: Excessive fatigue and lethargy can occur when anxiolytics (anti-anxiety and anti-panic drugs) drugs are combined with Surmontil.
  • Muscle relaxants: Concurrent use with this medication may cause excessive drowsiness and a feeling of fatigue.
  • Cough syrups: Cough syrups may contain an antihistamine and/or alcohol, which can cause extreme drowsiness when taken with this medication.
  • Nasal decongestants and respiratory stimulants: These agents taken with Surmontil may increase heart rate to an unsafe level.

Precautions and Warnings

Like many TCAs, Surmontil carries with it several significant risks of which to be aware. If you are prescribed this medication, make sure you cover the following information with your doctor:

  • This drug may cause changes in behavior, especially for children, and may result in increased suicidal thoughts or behaviors. Special attention should be paid to person’s mood at the beginning of treatment, when dosage is adjusted, and when withdrawing from the medication.
  • Use of this medication should be avoided by people recovering from the acute phase of myocardial infarction (heart attack). Discuss your entire heart history with your doctor before taking this drug.
  • Surmontil can increase the effects of catecholamine present in the body. This can worsen the effects of pheochromocytoma.
  • Surmontil lowers the seizure threshold and can increase the frequency of convulsions.
  • Due to the compromised function of the liver in hepatitis, the metabolism of Surmontil decreases for a person with this condition. Under these circumstances, dosage will need adjusted.
  • People with kidney impairment cannot remove the drug from the body. This can cause the accumulation of the active metabolite of this medication.
  • It is possible for this medication to excite symptoms associated with schizophrenia and bipolar. If you experience these conditions, make sure your doctor knows before prescribing you this medication.

How to Safely Withdraw

Do not try to reduce or stop this medicine abruptly without talking to your doctor. To reduce the severity and occurrence of withdrawal symptoms, it’s best to taper your dosage down gradually. Work with your health care provider to come up with the safest plan for you. Some withdrawal symptoms may include:

  • Malaise
  • Persistent headaches
  • Flu-like symptoms


  1. Katz, L.Y. et al. (2008). Effect of regulatory warnings on antidepressant prescription rates, use of health services and outcomes among children, adolescents and young adults. Canadian Medical Association Journal, 178(8), 1005.
  2. Bockting, C.L. et al. (2008). Continuation and maintenance use of antidepressants in recurrent depression. Psychotherapy and Psychosomatics, 77(1), 17.
  3. Bonisch, H. and Bruss, M. (2006). The norepinephrine transporter in physiology and disease. Handbook of Experimental Pharmacology, 175, 485.
  4. Castren, E., Voikar, V., and Rantamaki, T. (2007). Role of neurotrophic factors in depression. Current Opinion in Pharmacology, 7(1), 18.

Page content reviewed by James Pendleton, ND.