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Guanfacine

Guanfacine is used to treat hypertension (high blood pressure). It relaxes the heart and arteries, so blood passes through more efficiently. As a result, guanfacine reduces blood pressure to help prevent heart and kidney disease. People may also take guanfacine for ADHD.

Last Modified: May 11, 2023
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What Is Guanfacine?

Guanfacine belongs to the class of medicines known as centrally acting alpha 2A-adrenergic receptor agonists. In adults, it is used as an alternative agent to treat high blood pressure. In pediatric patients, it works as an adjuvant for the treatment of attention-deficit/hyperactivity disorder in addition to treating high blood pressure.

Guanfacine reduces heart rate and dilates blood vessels. As a result, the heart doesn’t have to work as hard to pump blood around the body, which lowers blood pressure.

Guanfacine’s exact method of treating ADHD in children and adolescents is unknown. However, doctors think it may affect brain receptors involved with distraction, inattention, working memory and impulse control. Guanfacine may also have antidepressant and anti-anxiety effects. Guanfacine is not a stimulant.

Guanfacine vs. Adderall

Both guanfacine and Adderall help treat ADHD, but they work differently. Guanfacine impacts the nerve receptors in the brain less directly than Adderall, which means it takes longer to work.

The most notable difference between guanfacine and Adderall is that the latter is a central nervous system stimulant. Stimulants may carry a risk of abuse or dependence and are classified as controlled substances. Although Adderall and guanfacine are both effective in treating ADHD, doctors usually prescribe stimulants first.

What Is Guanfacine Used For?

Doctors initially prescribed guanfacine for hypertension, either with other high blood pressure drugs or on its own. Hypertension, or high blood pressure, is a common condition that can lead to a heart attack, heart failure, stroke and many other health issues. 

In addition, guanfacine extended-release tablets effectively treat ADHD, particularly in combination with stimulant ADHD medications. Therefore, the U.S. Food and Drug Administration also approved guanfacine for ADHD on its own (monotherapy) and as an adjunctive to stimulants.

Some studies have shown that extended-release guanfacine is effective and safe in children and adolescents with generalized anxiety disorder. Guanfacine may be a good option for anxiety in children and adults.

How Does Guanfacine Work?

Guanfacine stimulates alpha2 adrenergic receptors in the brain. The stimulation reduces nerve impulses in the brain (in the vasomotor center) that lead to the heart and blood vessels. Since guanfacine reduces heart rate and dilates blood vessels, the heart doesn’t have to work as hard to pump blood around the body, which lowers blood pressure.

Guanfacine helps with ADHD symptoms that aren’t well managed with stimulants, such as impulsivity, emotional overreactions and hyperactivity. But it’s still unknown how guanfacine affects the brain. Guanfacine may be prescribed with a stimulant for ADHD in individuals between 6 and 17 years of age. This strategy is generally better for older children and adults.

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How to Take Guanfacine

For hypertension, dosing may start at 0.5-1 mg and increase up to 2 mg after three to four weeks. The recommended initial dose of Tenex (guanfacine hydrochloride) is 1 mg daily, taken alone or combined with another antihypertensive drug. It should be given at bedtime to minimize drowsiness. If, after three to four weeks of therapy, 1 mg does not give a satisfactory result, the daily dose may be increased to 2 mg.

To control ADHD symptoms, the ideal dose of Intuniv is between 4 and 7 mg/kg. Depending on clinical response and tolerability for Intuniv, the target dose range is 0.05-0.12 mg/kg/day (total daily dose between 1-7 mg). This dose helps balance the potential benefits and risks of guanfacine.

The table below provides the recommended target dose range for Intuniv based on body weight.

WeightTarget dose range (0.05 - 0.12 mg/kg/day)
55-74 pounds2-3 mg/day
75-91 pounds2-4 mg/day
92-108 pounds3-5 mg/day
109-128 pounds3-6 mg/day
129-200 pounds4-7 mg/day
>200 pounds5-7 mg/day

Doses above 4 mg/day have not been evaluated in children (ages 6-12 years), and doses over 7 mg/day have not been evaluated in adolescents (ages 13-17 years). The adjunctive trial evaluating Intuniv treatment with psychostimulants found that most patients reached optimal doses in the 0.05-0.12 mg/kg/day range. Doses above 4 mg/day have not been studied in adjunctive trials.

Guanfacine Side Effects

One of the main side effects of guanfacine is drowsiness or dizziness. For this reason, it’s best to take your daily dose at bedtime. Adults should also avoid taking the medication before driving until they know how it affects them. Sedation is a particular problem with many children.

Other side effects include irregular or pounding heartbeat, chest pain or discomfort, difficulty breathing, an increased need to urinate, abdominal pain and decreased appetite. In addition, some people may experience anxiety or nervousness and, in rare cases, hallucinations. Adults tend to tolerate guanfacine better then children and adolescents, based on studies.

What to Know Before Taking Guanfacine

Use caution before taking Intuniv if you have heart issues such as hypotension (low blood pressure), bradycardia, heart block or syncope (e.g., those taking antihypertensives). Your doctor will measure your heart rate and blood pressure before initiating therapy and periodically while taking guanfacine.

Avoid becoming dehydrated or overheated while taking guanfacine. Talk to your doctor before having surgery, including dental surgery, while taking guanfacine.

There are no studies on guanfacine while nursing or during pregnancy, so it is unknown whether this medication can harm an unborn fetus. Tell your doctor if you are breastfeeding, pregnant or plan to become pregnant.

The FDA has approved Intuniv for children over 6 years of age. This medication is not recommended for children under age 6. Additionally, the manufacturers of Tenex state that safety and effectiveness aren’t proven in children under 12 years of age, so Tenex in this age group is not recommended.

Talk to your doctor before taking guanfacine if you have a history of fainting, stroke, bipolar disorder or heart, kidney or liver disease.

Guanfacine Interactions

Avoid consuming grapefruit or grapefruit juice while taking guanfacine, as it may cause blood pressure to fall too low. Also, tell your doctor if you take any herbal products, such as St. John’s wort, to identify potential guanfacine interactions.

Because guanfacine may cause drowsiness, avoid other medications that can cause drowsiness.

Avoid or limit your consumption of alcohol during guanfacine treatment as it may increase the sedative effect.

If you’re taking a long-acting or extended-release formulation of the medication, do not take it with a high-fat meal. In addition, you should never chew or crush the tablets. Doing so may increase the absorption and blood levels of guanfacine.

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