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hydralazine/isosorbide dinitrate

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Brand names: BiDil

Vasodilator / Nitrate Combination Rx

BiDil is a medicine that combines two drugs to help treat heart failure. It contains isosorbide dinitrate and hydralazine hydrochloride, which work together to widen blood vessels.

Drug Pricing (NADAC)

Brand Price

$4.38/unit

Generic Available

No

Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →

What it does

BiDil is used to treat heart failure in self-identified Black patients.

Common side effects

Headache, Dizziness

Key warnings

BiDil can cause low blood pressure, especially when you stand up.

How It Works

BiDil contains two medicines that work in different ways to widen your blood vessels. Isosorbide dinitrate widens both arteries and veins. Hydralazine hydrochloride mainly widens arteries.

How to Take It

Start by taking one BiDil tablet three times a day. Your doctor may increase the dose up to two tablets three times a day, if you can handle it. If you have side effects, your doctor may lower the dose to one-half tablet three times a day. Try to increase the dose again as soon as the side effects get better.

Pregnancy & Breastfeeding

It is not known if BiDil is safe to use during pregnancy. Talk to your doctor if you are pregnant or plan to become pregnant. It is also not known if BiDil passes into breast milk. Talk to your doctor about the best way to feed your baby if you are taking BiDil.

Missed Dose

If you miss a dose, take it as soon as you remember. If it is close to your next dose, skip the missed dose and continue with your regular schedule.

Storage

Store BiDil tablets at room temperature (between 59°F and 86°F) in a tightly closed container, protected from light.

Side Effects (from patient reports)

Based on 17,575 FDA adverse event reports.

Long-term kidney disease
2,819
Sudden kidney damage
2,616
Kidney failure
2,097
Final stage of kidney failure
1,585
Tiredness
1,541
Shortness of breath
1,535
Diarrhea
1,406
Feeling sick to your stomach
1,334
The medicine is not working
1,326
Death
1,316

Serious Warnings

BiDil can cause low blood pressure, especially when you stand up. This is more likely if you are dehydrated or have low salt levels. Hydralazine hydrochloride, one of the medicines in BiDil, can cause a lupus-like syndrome. If you have symptoms, your doctor may tell you to stop taking BiDil. BiDil can also worsen chest pain, especially if you have certain heart conditions.

Known Drug Interactions

7 DRUG INTERACTIONS 7.1 Phosphodiesterase Inhibitors BiDil is contraindicated in patients who are using a selective inhibitor of cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE5), PDE5 inhibitors such as avanafil, sildenafil, vardenafil, and tadalafil have been shown to potentiate the hypotensive effects of organic nitrates.

Mechanism: Both drugs work to relax blood vessels, and taking them together can cause your blood pressure to drop to a dangerously low level.

What to do: Do not take these two medications together.

7 DRUG INTERACTIONS 7.1 Phosphodiesterase Inhibitors BiDil is contraindicated in patients who are using a selective inhibitor of cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE5), PDE5 inhibitors such as avanafil, sildenafil, vardenafil, and tadalafil have been shown to potentiate the hypotensive effects of organic nitrates.

Mechanism: These medicines both lower blood pressure in a similar way, and using them at the same time can cause a severe and unsafe drop in blood pressure.

What to do: You should not use these drugs together as it is strictly advised against.

Common Questions

What should I avoid while taking BiDil?
You should avoid taking PDE5 inhibitors (like sildenafil, tadalafil, vardenafil, or avanafil) or riociguat while taking BiDil, as this can cause dangerously low blood pressure.
Can I drive while taking BiDil?
BiDil can cause dizziness or lightheadedness. Be careful when driving or operating machinery until you know how BiDil affects you.
How long does it take for BiDil to work?
BiDil starts working right away to widen your blood vessels. It may take a few weeks to notice the full benefits, such as improved breathing and less swelling.
What if I have kidney problems?
There are no specific studies on BiDil in people with kidney problems. Talk to your doctor about whether BiDil is right for you.
What if I have liver problems?
Talk to your doctor if you have liver problems, as BiDil may need to be used with caution.
Can I take BiDil with other medications?
Tell your doctor about all the medications you take, including over-the-counter drugs and supplements, before starting BiDil.
What are the ingredients in BiDil?
Each BiDil tablet contains 20 mg of isosorbide dinitrate and 37.5 mg of hydralazine hydrochloride, along with inactive ingredients.
What do the tablets look like?
BiDil tablets are orange, film-coated, and have "20" on one side and "N" on the other.
How do I dispose of unused BiDil?
Talk to your pharmacist about the best way to dispose of unused BiDil. Do not flush it down the toilet.
What if I have side effects?
Tell your doctor if you have any side effects while taking BiDil. They may be able to adjust your dose or recommend other treatments.
What are the common side effects of hydralazine/isosorbide dinitrate?
The most commonly reported side effects of hydralazine/isosorbide dinitrate include Headache, Dizziness. Based on 17,575 FDA adverse event reports. Always consult your healthcare provider about potential side effects.
Does hydralazine/isosorbide dinitrate interact with other medications?
Yes, hydralazine/isosorbide dinitrate has 2 known drug interactions. Notable interactions include sildenafil, tadalafil. Always inform your doctor about all medications you are taking.
What drug class is hydralazine/isosorbide dinitrate?
hydralazine/isosorbide dinitrate belongs to the Vasodilator / Nitrate Combination drug class. It requires a prescription (Rx). BiDil is used to treat heart failure in self-identified Black patients.
Is hydralazine/isosorbide dinitrate safe during pregnancy?
It is not known if BiDil is safe to use during pregnancy. Talk to your doctor if you are pregnant or plan to become pregnant. Always consult your healthcare provider before using any medication during pregnancy or breastfeeding.

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What the FDA Data Shows for hydralazine/isosorbide dinitrate

The FDA label for hydralazine/isosorbide dinitrate (sold under brand names such as BiDil) classifies it as a prescription-only medication in the Vasodilator / Nitrate Combination class. BiDil is used to treat heart failure in self-identified Black patients. Official labeling lists 2 commonly reported side effects, including Headache, Dizziness.

Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 17,575 voluntary reports. The database also lists 2 documented drug interactions derived from FDA labeling, with the top-flagged interaction rated major severity. NADAC pricing from CMS.

Report counts do not establish causation — a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history, and patent information further shape supply and switching decisions. This page summarizes public FDA data for educational purposes only and is not a substitute for professional medical advice — always consult a licensed healthcare provider before starting, stopping, or changing any medication.

Data Sources

Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS). Pricing: CMS National Average Drug Acquisition Cost (NADAC).

FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. Always consult a healthcare professional before making medication decisions.

Last updated: November 30, 2025

All federal data sources used on this page