clonidine vs guanfacine
Side-by-side comparison of clonidine and guanfacine Data from FDA drug databases (Orange Book, NDC Directory, recalls, shortages) covering 20,000+ approved drugs, plus CMS pricing; see our methodology.
Catapres
Intuniv, Tenex
Clonidine (Catapres) is a medicine used to treat high blood pressure. It can be used alone or with other blood pressure medicines.
Guanfacine extended-release tablets can help treat ADHD. It can be used alone or with stimulant medicines.
Clonidine is used to treat high blood pressure. High blood pressure can lead to heart disease, stroke, and kidney problems. This medicine helps to lower your blood pressure to a safer level.
Guanfacine extended-release tablets are used to treat Attention Deficit Hyperactivity Disorder (ADHD). It can be used by itself or with other stimulant medicines to help manage ADHD symptoms. This medicine works by affecting certain receptors in the brain.
Clonidine works in the brain to lower blood pressure. It tells your blood vessels to relax and widen. This makes it easier for blood to flow through your body, which lowers blood pressure.
Guanfacine is a central alpha 2A-adrenergic receptor agonist. This means it works by stimulating specific receptors in the brain. By stimulating these receptors, guanfacine helps to improve attention and reduce impulsivity and hyperactivity in people with ADHD.
- • Dry mouth (occurs in about 40 out of 100 people)
- • Drowsiness (occurs in about 33 out of 100 people)
- • Dizziness (occurs in about 16 out of 100 people)
- • Constipation (occurs in about 10 out of 100 people)
- • Feeling sleepy or sedated (occurs in about 10 out of 100 people)
- • Feeling sleepy or tired
- • Low blood pressure
- • Dizziness
- • Upset stomach
- • Dry mouth
- The medicine is not working 3,869
- Pain 3,038
- Tiredness 2,922
- Feeling sick to your stomach 2,918
- Using the medicine for something it's not approved for 2,853
- The medicine is not working 778
- Using the medicine for a condition it is not approved for 598
- Sleepiness 455
- Being aggressive 376
- Feeling tired 330
If you suddenly stop taking clonidine, your blood pressure may increase. This can cause serious problems. Talk to your doctor before stopping this medicine.
Guanfacine can cause low blood pressure, slow heart rate, and fainting. Tell your doctor if you have heart problems. This medicine can also cause sleepiness, so be careful driving or using heavy machinery. Stopping guanfacine suddenly can cause high blood pressure. Your doctor will slowly lower your dose when you stop taking it.
Tell your doctor if you are pregnant or plan to become pregnant. It is not known if clonidine will harm your unborn baby. Talk to your doctor if you are breastfeeding.
Tell your doctor if you are pregnant or plan to become pregnant. There is a pregnancy registry for women who take ADHD medicines during pregnancy. Talk to your doctor if you are breastfeeding or plan to breastfeed. Monitor breastfed infants for sleepiness, lethargy, and poor feeding.
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How to Read This clonidine vs guanfacine Comparison
clonidine is classified in the Central Alpha-2 Agonist drug class, while guanfacine sits within the Central Alpha-2 Agonist class. Because both drugs share the same classification, they are often considered interchangeable in theory — but clinical outcomes rarely track that cleanly. Both drugs are prescription-only, so a licensed provider must authorize use.
Adverse event totals above are pulled from the FDA's Adverse Event Reporting System (FAERS). For these top-ranked reactions alone, clonidine has 15,600 submissions while guanfacine has 2,537. Those figures reflect cumulative reporting volume — not per-patient risk — so older, widely dispensed drugs typically look worse on count alone. No direct interaction between these two drugs is listed in our FDA-derived dataset, though co-prescription still warrants pharmacist review. Serious warnings, pregnancy guidance, and contraindications can differ even when indications overlap.
A table cannot substitute for clinical judgment. Effectiveness, tolerability, drug-drug interactions with your other medications, kidney and liver function, pregnancy status, insurance formulary, and price all feed into a decision that only a licensed prescriber can make responsibly. Data here is sourced from FDA Structured Product Labels (SPL) and FAERS, both of which update as manufacturers and clinicians submit new information. This page is for educational purposes only, is not medical advice, and should not be used to self-switch between clonidine and guanfacine — always consult your physician or pharmacist first.
Important: This comparison is for informational purposes only. Drug effects vary between individuals. Always consult your doctor or pharmacist for personalized medical advice.