guanfacine vs methyldopa
Side-by-side comparison of guanfacine and methyldopa Data from FDA drug databases (Orange Book, NDC Directory, recalls, shortages) covering 20,000+ approved drugs, plus CMS pricing; see our methodology.
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Guanfacine extended-release tablets can help treat ADHD. It can be used alone or with stimulant medicines.
Methyldopa is a medicine used to treat high blood pressure. It helps to lower your blood pressure.
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.
Methyldopa is used to treat hypertension, which is also known as high blood pressure. High blood pressure can strain the heart and blood vessels. Lowering blood pressure can reduce the risk of strokes, heart attacks, and kidney problems.
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.
Methyldopa lowers blood pressure by affecting certain chemicals in your brain. These chemicals help to relax blood vessels, which allows blood to flow more easily. This results in lower blood pressure.
- • Feeling sleepy or tired
- • Low blood pressure
- • Dizziness
- • Upset stomach
- • Dry mouth
- • Sedation
- • Headache
- • Weakness
- 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
- Baby exposed to drug during pregnancy 1,261
- Baby born too early 888
- Mother exposed to drug during pregnancy 794
- Exposure to drug during pregnancy 654
- Delivery before term 561
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.
You should not take methyldopa if you have active liver disease like hepatitis or cirrhosis. Also, do not take it if you have had liver problems caused by methyldopa in the past. Do not take it if you are allergic to any of the ingredients in methyldopa. You should not take this medicine if you are taking a monoamine oxidase (MAO) inhibitor.
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.
Tell your doctor if you are pregnant, plan to become pregnant, or are breastfeeding. Methyldopa can pass into breast milk. Talk to your doctor about the risks and benefits.
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How to Read This guanfacine vs methyldopa Comparison
guanfacine is classified in the Central Alpha-2 Agonist drug class, while methyldopa 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, guanfacine has 2,537 submissions while methyldopa has 4,158. 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 guanfacine and methyldopa — 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.