Vitamin K and anaphylaxis: what to know

Anaphylaxis can develop quickly after exposure to an injected or oral product. Warning signs include swelling of the lips, tongue or throat, trouble breathing, wheezing, widespread hives, sudden dizziness, collapse, vomiting or a feeling that something is seriously wrong. Symptoms may involve more than one body system, but a serious breathing or circulation problem can be enough to require emergency treatment.

The reaction may be caused by vitamin K or another ingredient in the product. Do not assume a previous mild reaction predicts what will happen next. A clinician or allergy specialist can review the product, timing and symptoms and decide whether allergy testing is useful.

If anaphylaxis is suspected, use an adrenaline auto-injector if one has been prescribed, call emergency services, and state that anaphylaxis is suspected. Follow the device instructions, lie down with legs raised if possible, or sit up slowly if breathing is difficult. Do not stand or walk around. If symptoms continue and another prescribed injector is available, follow emergency guidance while waiting for help.

Avoid further vitamin K exposure until a clinician has reviewed the reaction. Keep the packaging, product name and timing information for the medical team.

Emergency help is needed for breathing difficulty, throat or tongue swelling, faintness, collapse, widespread symptoms or rapid worsening after vitamin K. A person who improves after adrenaline still needs medical assessment because symptoms can return.

Ask whether the suspected trigger was vitamin K or an added ingredient, whether you need an adrenaline plan, which products to avoid, and how to document the allergy for future care.