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Nitropress Side Effects Center

Medical Editor: John P. Cunha, DO, FACOEP

Nitropress (sodium nitroprusside) Injection, Solution, Concentrate is used to treat congestive heart failure and life-threatening high blood pressure (hypertension). It is also used to keep blood pressure low during a surgery. Nitropress is a vasodilator. Common side effects include skin rash, warmth, redness, or tingly feeling under your skin, darkening or deeper color of veins through your skin, or pain or irritation where the needle is placed.

Nitropress is administered as an injection. The average effective rate in adults and children is about 3 mcg/kg/min, but should be started at a very low rate of 0.3 mcg/kg/min, and increased until the desired effect is achieved or the maximum recommended infusion rate of 10 mcg/kg/min has been reached. Nitropress may interact with blood pressure medications. There may be other drugs that can affect Nitropress. Tell your doctor about all the prescription and over-the-counter medications or supplements you use. Nitropress should be taken during pregnancy only if prescribed. This medication may be harmful to a fetus. This medication may pass into breast milk and could harm a nursing baby. Consult your doctor before breast-feeding.

Our Nitropress (sodium nitroprusside) Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What is Patient Information in Detail?

Easy-to-read and understand detailed drug information and pill images for the patient or caregiver from Cerner Multum.

Nitropress in Detail - Patient Information: Side Effects

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Tell your caregivers at once if you have a serious side effect such as:

  • feeling like you might pass out, even while lying down;
  • gasping, struggling to breathe, or shallow breathing;
  • confusion, ringing in your ears;
  • dizziness with nausea and vomiting, rapid breathing, seizure (convulsions);
  • fast, slow, or uneven heart rate;
  • numb or cold feeling in your arms and legs; or
  • chills, sweating, tremors, twitching, overactive reflexes.

Less serious side effects may include:

  • mild skin rash;
  • mild stomach pain or nausea;
  • warmth, redness, or tingly feeling under your skin;
  • darkening or deeper color of veins through your skin; or
  • irritation around the IV needle.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Read the entire detailed patient monograph for Nitropress (Nitroprusside Sodium)

What is Prescribing information?

The FDA package insert formatted in easy-to-find categories for health professionals and clinicians.

Nitropress FDA Prescribing Information: Side Effects
(Adverse Reactions)


The most important adverse reactions to sodium nitroprusside are the avoidable ones of excessive hypotension and cyanide toxicity, described above under WARNINGS. The adverse reactions described in this section develop less rapidly and, as it happens, less commonly.


As described in CLINICAL PHARMACOLOGY above, sodium nitroprusside infusions can cause sequestration of hemoglobin as methemoglobin. The back-conversion process is normally rapid, and clinically significant methemoglobinemia ( < 10%) is seen only rarely in patients receiving NITROPRESS. Even patients congenitally incapable of back-converting methemoglobin should demonstrate 10% methemoglobinemia only after they have received about 10 mg/kg of sodium nitroprusside, and a patient receiving sodium nitroprusside at the maximum recommended rate (10 mcg/kg/min) would take over 16 hours to reach this total accumulated dose.

Methemoglobin levels can be measured by most clinical laboratories. The diagnosis should be suspected in patients who have received < 10 mg/kg of sodium nitroprusside and who exhibit signs of impaired oxygen delivery despite adequate cardiac output and adequate arterial pO2. Classically, methemoglobinemic blood is described as chocolate brown, without color change on exposure to air.

When methemoglobinemia is diagnosed, the treatment of choice is 1-2 mg/kg of methylene blue, administered intravenously over several minutes. In patients likely to have substantial amounts of cyanide bound to methemoglobin as cyanmethemoglobin, treatment of methemoglobinemia with methylene blue must be undertaken with extreme caution.

Thiocyanate Toxicity

As described in CLINICAL PHARMACOLOGY above, most of the cyanide produced during metabolism of sodium nitroprusside is eliminated in the form of thiocyanate. When cyanide elimination is accelerated by the co-infusion of thiosulfate, thiocyanate production is increased.

Thiocyanate is mildly neurotoxic (tinnitus, miosis, hyperreflexia) at serum levels of 1 mmol/L (60 mg/L). Thiocyanate toxicity is life-threatening when levels are 3 or 4 times higher (200 mg/L).

The steady-state thiocyanate level after prolonged infusions of sodium nitroprusside is increased with increased infusion rate, and the half-time of accumulation is 3-4 days. To keep the steady-state thiocyanate level below 1 mmol/L, a prolonged infusion of sodium nitroprusside should not be more rapid than 3 mcg/kg/min; in anuric patients, the corresponding limit is just 1 mcg/kg/min. When prolonged infusions are more rapid than these, thiocyanate levels should be measured daily.

Physiologic maneuvers (e.g., those that alter the pH of the urine) are not known to increase the elimination of thiocyanate. Thiocyanate clearance rates during dialysis, on the other hand, can approach the blood flow rate of the dialyzer.

Thiocyanate interferes with iodine uptake by the thyroid.

Abdominal pain, apprehension, diaphoresis, “dizziness,” headache, muscle twitching, nausea, palpitations, restlessness, retching, and retrosternal discomfort have been noted when the blood pressure was too rapidly reduced. These symptoms quickly disappeared when the infusion was slowed or discontinued, and they did not reappear with a continued (or resumed) slower infusion.

Other adverse reactions reported are:

Cardiovascular: Bradycardia, electrocardiographic changes, tachycardia.

Dermatologic: Rash.

Endocrine: Hypothyroidism.

Gastrointestinal: Ileus.

Hematologic: Decreased platelet aggregation.

Neurologic: Increased intracranial pressure.

Miscellaneous : Flushing, venous streaking, irritation at the infusion site.

Read the entire FDA prescribing information for Nitropress (Nitroprusside Sodium)

Report Problems to the Food and Drug Administration


You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

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