Supplements and Guanfacine.
Guanfacine, sold under the brand name Intuniv, is classified under "adhd non stimulant" in the BNF.
Guanfacine (brand names Intuniv) sits in the Distil medication database. The BNF classifies it under "adhd non stimulant". This means it sits outside the high-volume therapeutic classes (statins, PPIs, ACE inhibitors, SSRIs) where supplement-interaction surfaces are densely studied, and the published evidence base for specific supplement pairs is correspondingly thinner. Where interactions are documented in the Distil database, they are listed below with their clinical-reference citation; where pairs have not been explicitly assessed, the missing-item form at the bottom of the page routes them into our next curation pass. Anyone combining Guanfacine with a regular supplement stack benefits from explicit GP or pharmacist awareness rather than assuming no interaction exists by default.
Below are the 10 documented pairs we have explicitly assessed against Guanfacine in the Distil database: 10 caution. The pairs cluster around 2 mechanisms: Additive blood-pressure lowering and Additive CNS depression. Every call is cited to either a clinical reference (PMID) or the British National Formulary. Anything not on this list is either still to be assessed or beyond our database scope. The checker beneath surfaces assessments by supplement, and the missing-item form at the bottom of the page routes any uncatalogued supplement into our next curation pass.
Documented interactions
Last reviewed 13 October 2026. Each interaction below lists the evidence its assessment drew on: some rest on studies of the exact pair, others on mechanism evidence, where a citation may support one part of the reasoning rather than the exact combination. The evidence line on each entry says which.
Additive blood-pressure lowering
Caution Does Beetroot Extract interact with Guanfacine?
Beetroot lowers blood pressure through the nitric oxide pathway, and guanfacine lowers it by reducing the nerve signals that drive blood pressure up. Used together, the combined effect tends to be a little larger than either alone. Watch for dizziness on standing, especially in the first two weeks. If symptoms appear, tell your GP.
Evidence: Limited human data, from small studies or case reports.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Caution Does Garlic Extract interact with Guanfacine?
Garlic supplements may lower blood pressure a little, mostly when it is above target, and guanfacine lowers it too, so together they may bring it down a bit further. If you feel dizzy or light-headed, especially when you stand up, check your blood pressure and tell your GP. Garlic's effect tends to build over several weeks, so keep an eye on your readings for the first three months or so.
Evidence: Limited human data, from small studies or case reports.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Caution Does Hibiscus Extract interact with Guanfacine?
Hibiscus tends to lower blood pressure on its own, and guanfacine lowers it too. Taken together the blood-pressure effects may stack, so watch for dizziness on standing, especially in the first couple of weeks. If symptoms appear, tell your GP.
Evidence: Limited human data, from small studies or case reports.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Caution Does L-Citrulline interact with Guanfacine?
L-citrulline mildly lowers blood pressure by raising nitric oxide, and guanfacine lowers it by reducing the nerve signals that drive blood pressure up. Taken together the effects may stack, so watch for dizziness on standing, especially in the first couple of weeks. The added effect tends to be modest. If symptoms appear, tell your GP.
Evidence: Limited human data, from small studies or case reports.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Caution Does Taurine interact with Guanfacine?
Taurine tends to lower blood pressure on its own, and guanfacine lowers it too. Taken together the blood-pressure effects may stack, so watch for dizziness on standing, especially in the first couple of weeks. Taurine's own effect on blood pressure is small. If symptoms appear, tell your GP.
Evidence: Limited human data, from small studies or case reports.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Additive CNS depression
Caution Does Ashwagandha interact with Guanfacine?
Ashwagandha can have a calming, mildly sedating effect and improves sleep for some people, and guanfacine commonly causes drowsiness and tiredness. Taken together they may add to the sedation. Use with care, particularly around driving, and especially in the first weeks.
Evidence: No direct study of this exact combination yet; the caution rests on a plausible mechanism or on reports involving a related medicine.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Caution Does Lemon Balm interact with Guanfacine?
Lemon balm can make you drowsy, and guanfacine commonly causes drowsiness and tiredness too. Taken together they may add to the sedation and slow your reactions more than either alone. Use with care, particularly around driving, and especially in the first weeks.
Evidence: No direct study of this exact combination yet; the caution rests on a plausible mechanism or on reports involving a related medicine.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Caution Does Melatonin interact with Guanfacine?
Melatonin and guanfacine can both promote drowsiness, so taking them together may add to the sedation and slow your reaction time more than either does alone. Use with care, particularly around driving.
Evidence: No direct study of this exact combination yet; the caution rests on a plausible mechanism or on reports involving a related medicine.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Caution Does Passionflower interact with Guanfacine?
Passionflower can make you drowsy, and guanfacine commonly causes drowsiness and tiredness too. Taken together they may add to the sedation and slow your reactions more than either alone. Use with care, particularly around driving, and especially in the first weeks.
Evidence: No direct study of this exact combination yet; the caution rests on a plausible mechanism or on reports involving a related medicine.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Caution Does Valerian Root interact with Guanfacine?
Valerian can make you drowsy, and guanfacine commonly causes drowsiness and tiredness too. Taken together they may add to the sedation and slow your reactions more than either alone. Use with care, particularly around driving or operating machinery, and especially in the first weeks.
Evidence: No direct study of this exact combination yet; the caution rests on a plausible mechanism or on reports involving a related medicine.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
What this list does not say. Pairs not flagged here are not implicitly safe. They are either not yet in our database, or fall outside our inclusion scope (food-supplement interactions only; for drug-drug interactions, the BNF is authoritative). Use the checker below to surface any supplement, and submit a missing item if you take something we have not catalogued.
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How the checker decides
Every result has a source
Each pair we have assessed is cited to a published study (PMID) or the British National Formulary, so you can read the source yourself.
Four kinds of answer
Severe, caution, no known interaction, and not yet assessed. A pair we have not assessed is never shown as clear.
- Severe
- Caution
- No known interaction
- Not yet assessed
Nothing in our data is not a clearance
When nothing in our data records a problem with a pair, the result says no known interaction at typical doses, which is not a clearance: your pharmacist or GP can check the pair against your full medical history.
A full supplement review, built around you, not a generic stack.
The free checker answers one interaction question at a time. A Distil report reviews the bigger picture: your goals, diet, medications, current supplements and any blood results you provide, then shows what appears worth keeping, changing, adding or leaving out.
- what your diet already covers, so you are not adding a capsule for something food is already handling
- which evidence-graded compounds are worth considering for your goals, and which were considered but left out
- what to keep, change or stop from what you already take, plus the order to introduce anything new
- how your medications and complete supplement stack fit together, with daily timing and a clear point for reassessment
The interaction check is one section of the full report. You also get the reasoning behind each recommendation and the evidence references used.
£49 until 30 June 2027 · £79 from 1 July 2027.
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