Guanfacine ER Drug Interactions
Guanfacine ER can interact with prescription medications, over-the-counter products, supplements, and certain foods. Most interactions are manageable when your pharmacist knows your full medication list.
Common interaction categories to flag with your pharmacist
Other prescription medications
Bring a current list of every prescription you take when filling Guanfacine ER. Common interactions involve blood thinners, antibiotics, antidepressants, and pain medications.
Over-the-counter products
OTC products like NSAIDs, antacids, cold/flu remedies, and sleep aids can interact with Guanfacine ER. Confirm with your pharmacist before combining.
Supplements and herbal products
Common offenders include St John's wort, garlic, ginkgo, high-dose vitamins, and mineral supplements. Disclose all supplements when filling Guanfacine ER.
Foods and beverages
Grapefruit, leafy greens (vitamin K), tyramine-rich foods, and others can interact with specific medications. Ask whether any apply to Guanfacine ER.
Alcohol
Alcohol interacts with many medications, sometimes seriously. See our dedicated Guanfacine ER and alcohol guide.
Caffeine and stimulants
Caffeine, energy drinks, and other stimulants can interact with some Guanfacine ER use cases. Check with your pharmacist if you consume regularly.
How to check $Guanfacine ER interactions safely
- Give your pharmacist a complete list of everything you take — prescription, OTC, supplements, herbal.
- Update your pharmacy profile whenever you start or stop a medication.
- Use a single pharmacy when possible — the pharmacist's system flags interactions automatically.
- Read the patient information leaflet that comes with Guanfacine ER.
- Call your pharmacist before starting any new product — they're trained interaction specialists.
Symptoms that suggest an interaction
Unusual drowsiness, rapid heart rate, blood pressure changes, severe GI symptoms, unusual bleeding, or any reaction that feels new — call your pharmacist or prescriber immediately.
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Guanfacine ER interactions: FAQs
What medications interact with Guanfacine ER?
Guanfacine ER can interact with many prescription medications, OTC products, supplements, and herbal remedies. Before starting Guanfacine ER, give your pharmacist a complete list of everything you take — they'll flag any clinically significant interactions.
Can I take Guanfacine ER with over-the-counter medications?
Some OTC medications interact with Guanfacine ER and others don't. Common ones to ask about: NSAIDs, antacids, cold/flu products, and any sleep aids. Confirm with your pharmacist before combining.
Are there supplements I should avoid while taking Guanfacine ER?
Supplements and herbal products can interact with Guanfacine ER — common examples include St John's wort, grapefruit-related products, and high-dose vitamins. Always disclose supplements to your pharmacist.
What should I do if I've started a new medication and I'm on Guanfacine ER?
Whenever you start any new prescription, OTC, or supplement, mention Guanfacine ER to the prescriber or pharmacist. Most interactions are manageable with timing changes or dose adjustments.
Where do I find the lowest cash price for Guanfacine ER?
Compare cash prices across local pharmacies before filling. ScriptUnlock surfaces the lowest available for Guanfacine ER among participating pharmacies.