Alternatives to Cyanokit If You Can't Fill Your Prescription

Cyanokit (hydroxocobalamin for injection) is the preferred antidote for cyanide poisoning in the United States, but the ongoing shortage that began in 2024 has left many hospitals and EMS agencies searching for reliable alternatives. This guide reviews each FDA-approved option, how it compares to hydroxocobalamin, and the critical clinical factors that should guide your decision.

Important note: This article is intended for healthcare providers. If you suspect cyanide poisoning, call 1-800-222-1222 (Poison Control) immediately. Do not delay treatment to look up alternatives.

Why Cyanokit Is the Preferred First-Line Antidote

Hydroxocobalamin (Cyanokit) earned its position as the preferred cyanide antidote through a combination of efficacy, safety, and versatility. An expert consensus panel in 2018 confirmed this preference. Key advantages include:

• Does not impair hemoglobin's ability to carry oxygen — safe for concurrent carbon monoxide poisoning (common in fire victims)
• Rapid onset of action — binds cyanide directly, with IV distribution into tissue compartments
• May help correct hypotension through nitric oxide binding (vasoconstriction)
• Safe in patients with G6PD deficiency, anemia, and pre-existing hypoxia
• Conducive to prehospital use — can be administered in the field by paramedics

Alternative 1: Nithiodote (Sodium Nitrite + Sodium Thiosulfate)

Nithiodote is an FDA-approved two-drug cyanide antidote kit containing sodium nitrite and sodium thiosulfate. It has been used in cyanide poisoning treatment for over 100 years and remains the most established alternative to Cyanokit.

How it works: Sodium nitrite is given first — it oxidizes hemoglobin to form methemoglobin, which preferentially binds cyanide, pulling it away from cytochrome oxidase. Sodium thiosulfate follows — it donates a sulfur group that the enzyme rhodanese uses to convert cyanide into thiocyanate, a less toxic compound excreted by the kidneys.

Dosing: Sodium nitrite 300 mg (10 mL of 3% solution) IV over 2–4 minutes, followed immediately by sodium thiosulfate 12.5 g (50 mL of 25% solution) IV over 10 minutes. A second dose may be given at half the original dose if symptoms return.

Critical limitation: Sodium nitrite intentionally reduces the blood's oxygen-carrying capacity by producing methemoglobin. This is dangerous for smoke inhalation victims who also have carbon monoxide poisoning — CO already impairs oxygen delivery, and adding methemoglobin can push oxygen levels to critically low levels. Sodium nitrite is also associated with hypotension.

Best used when: Cyanokit is unavailable AND the patient does not have concurrent CO poisoning, pre-existing anemia, or significant hypoxia. Appropriate for cyanide salt ingestion and industrial non-fire exposures.

Alternative 2: Sodium Thiosulfate Alone

Sodium thiosulfate can be used alone as an alternative when Cyanokit is unavailable and sodium nitrite is contraindicated (e.g., smoke inhalation with CO exposure). It does not impair oxygen-carrying capacity, making it safer in fire victims.

Limitation: Slower onset than hydroxocobalamin (reversal of cyanide toxicity may take up to 30 minutes). Poor intracellular penetration and short half-life limit its effectiveness as a monotherapy for severe cyanide poisoning. It is best used as an adjunct to hydroxocobalamin or, when used alone, given immediately while monitoring for persistent toxicity signs.

Combination Therapy: Hydroxocobalamin + Sodium Thiosulfate

When limited Cyanokit supply is available, some toxicologists recommend combining a partial dose of hydroxocobalamin with sodium thiosulfate. The two drugs have theoretically synergistic mechanisms and can be combined safely — they must NOT be mixed in the same IV line (use separate lines), but they are not pharmacologically incompatible in the same patient.

However, clinical evidence for this combination specifically in shortage scenarios is limited. Consult your regional poison control center for real-time guidance on dosing strategy.

Decision Framework: Choosing the Right Alternative

When Cyanokit is unavailable, your alternative should be guided by the patient's exposure scenario:

• Smoke inhalation victim (likely concurrent CO poisoning): Use sodium thiosulfate alone. Avoid sodium nitrite. Consider sodium thiosulfate 12.5 g IV immediately; if patient remains critically ill, nitrite may be considered with extreme caution and BP monitoring.
• Industrial/occupational cyanide exposure (no CO): Nithiodote (sodium nitrite + sodium thiosulfate) is appropriate. Follow Nithiodote dosing protocol with BP monitoring.
• Cyanide salt ingestion: Nithiodote with activated charcoal if patient is awake and can protect airway. Sodium thiosulfate alone for patients with anemia or other contraindications to nitrite.

Supportive Care in All Cases

Regardless of antidote choice, immediate supportive care is essential: 100% oxygen via non-rebreather mask or intubation, airway protection, hemodynamic support, and seizure management. These measures should not be delayed to wait for antidote administration.

Sourcing Available Cyanokit Before an Emergency

The best alternative to using a backup antidote is securing Cyanokit before you need it. medfinder for providers helps hospitals and EMS agencies locate available Cyanokit supply in their region without making dozens of individual supplier calls. Check out our guide on how to find Cyanokit in stock for more sourcing strategies.