Guanfacine and Imipramine: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Imipramine
No brand names on recordGuanfacine
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Decreased antihypertensive effectiveness
Interaction Deep Dive
Concomitant clonidine and tricyclic antidepressant (TCA) therapy may impair the antihypertensive effects of clonidine. Since the mechanism of action of guanfacine is similar to clonidine, patients stabilized on guanfacine should be monitored for a hypertensive response when TCA (i.e. desipramine or imipramine) therapy is started23. A case has been reported of a patient maintained on guanfacine who developed an increase in blood pressure when imipramine was added to therapy. When imipramine was discontinued, her blood pressure returned to baseline 4.
Why it happens (mechanism)
Unknown
Literature reports
2 reports — tap to read
a) A case of a hypertensive female who was maintained on guanfacine 2 mg daily with mean blood pressure at 138/89 mm Hg was reported 1. After amitriptyline 75 mg daily was begun, her mean blood pressure was 150/100 mm Hg; upon discontinuation of the amitriptyline, the blood pressure returned to 136/91 mm Hg. A month later she was given imipramine 50 mg daily and experienced similar changes in loss of blood pressure control; upon discontinuation of imipramine, the blood pressure again returned to 137/90 mm Hg.
b) Concomitant clonidine and tricyclic antidepressant therapy may impair the antihypertensive effects of clonidine. Since the mechanism of action of guanfacine is similar to clonidine, patients stabilized on guanfacine should be monitored for a hypertensive response when desipramine therapy is started 23.
Common questions
Can I take Guanfacine and Imipramine together?
Decreased antihypertensive effectiveness Always confirm with your pharmacist or prescriber before making any change.
How serious is the Guanfacine and Imipramine interaction?
It is rated moderate. Can be significant — usually manageable with monitoring.
How quickly could this interaction happen?
The documented onset is "delayed". Effects tend to build up gradually over days to weeks.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Guanfacine or Imipramine need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there anything you'd monitor while I'm on both?
References (4)
- Buckley M & Feely J: Antagonism of antihypertensive effect of guanfacine by tricyclic antidepreseants (letter). Lancet 1991; 337:1173-1174.
- Briant RH, Reid JL, & Dollery CT: Interaction between clonidine and desipramine in man. Br Med J 1973; 1:522-523. PubMed
- Hui KK: Hypertensive crisis induced by interaction of clonidine with imipramine. J Am Geriatr Soc 1983; 31:164-165. DOI
- Buckley M & Feely J: Antagonism of antihypertensive effect of guanfacine by tricyclic antidepressants (letter). Lancet 1991; 337:1173-1174. PubMed
Keep reading about Imipramine
Keep reading about Guanfacine
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Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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