Can Vitamin C Be Given Intramuscularly?
Yes, vitamin C can be administered intramuscularly when oral administration is not feasible or when malabsorption is suspected. 1
Routes of Administration
The 2022 ESPEN micronutrient guideline explicitly states that vitamin C "may be administered IM, IV, or subcutaneously when malabsorption is suspected" 1. This establishes IM administration as a recognized and appropriate route for vitamin C delivery in clinical practice.
When to Consider IM Administration
Intramuscular vitamin C is specifically indicated in the following situations:
- Malabsorption syndromes - When enteral uptake is compromised or unpredictable 1
- Suspected deficiency requiring rapid repletion - When oral absorption may be insufficient
- Clinical scurvy - When immediate treatment is needed and oral route is inadequate 1
- Bariatric surgery patients with vitamin A deficiency not responding to oral treatment - Though this guideline refers to vitamin A, it establishes the principle that IM fat-soluble vitamins are used when oral therapy fails 2
Important Administration Considerations
When administering vitamin C via IM route:
- Dilution is recommended - For IV injection (and by extension IM), the drug should be diluted with normal saline or glucose to minimize adverse reactions 1
- Pain at injection site - Be aware that IM injections can be painful, as documented in studies of vitamin A IM administration in preterm infants 3
Preferred Routes by Clinical Context
The evidence shows a clear hierarchy of preferred routes:
For routine supplementation: Oral administration is standard 1
For critical illness/severe deficiency: IV administration is strongly preferred over IM, with recommendations for 2-3 g/day IV during acute inflammation 1. The guideline emphasizes that "during critical illness, IV administration is crucial, as enteral uptake is unpredictable" 1
For malabsorption without critical illness: IM, IV, or subcutaneous routes are all acceptable alternatives 1
Clinical Caveat
While IM administration is feasible and recognized in guidelines, IV administration is generally preferred when parenteral vitamin C is needed, particularly in critical illness or when high doses are required for repletion. The IM route serves as a practical alternative when IV access is not available or for maintenance dosing in malabsorption states.