Vitamin C can decrease pain
It was interesting to read in the Journal the article by Mathieson et al., on “Pregabalin and Gabapentin for Pain”,  but surprising to find no mention of the use of vitamin C as it has been shown to enhance the analgesic effect of gabapentin with neuropathic pain, at least in rats.  In other studies of post-operative treatment of patients with vitamin C showed that it helped to reduce requirements for an analgesic, to improve VAS scores, and to achieve better functional outcomes following foot and ankle trauma surgery.  The Lancet published a clinical trial in 1999 showing the analgesic effect of vitamin C on reflex sympathetic dystrophy (or complex regional pain syndrome) following wrist fractures alone.  And these results were confirmed in subsequent publications. [5,6] Furthermore, plasma levels of vitamin C are lower in postherpetic neuralgia patients and administration of vitamin C was shown to reduce spontaneous pain. 
In their detailed review of the role of vitamin C in the treatment of pain, Carr and McCall  reported mainly human studies on the association of low plasma levels of vitamin C and increased pain, as well as the use of vitamin C (ranges 0.5 to 2g) as an analgesic in various painful medical conditions pre and post-surgery. They reported also its use to decrease opioid treatment. With the considerable concerns on the “opioid crisis of unprecedented proportions” dealing with ‘prescription opioid overuse’ it appears that vitamin C should be an appropriate, necessary, and relatively cheap, additional analgesic treatment, to both reduce pain and perhaps to reduce patient dependence on opioids.
I declare no competing interests.
Simon N. Thornton
Université de Lorraine and INSERM U_1116, Vandoeuvre les Nancy, France
1. Mathieson S, Lin CWC, Underwood M, Eldabe S. Pregabalin and Gabapentin for Pain. BMJ 2020 28;369:m1315. doi: 10.1136/bmj.m1315.
2. Li R, Shen L, Yu X, Ma C, Huang Y. Vitamin C enhances the analgesic effect of gabapentin on rats with neuropathic pain. Life Sci. 2016 157:25-31. doi: 10.1016/j.lfs.2016.05.035.
3. Jain SK, Dar MY, Kumar S, et al. Role of anti-oxidant (vitamin-C) in post-operative pain relief in foot and ankle trauma surgery: A prospective randomized trial. Foot Ankle Surg 2018 pii: S1268-7731(18)30159-0.
4. Zollinger PE, Tuinebreijer WE, Kreis RW, Breederveld RS. Effect of vitamin C on frequency of reflex sympathetic dystrophy in wrist fractures: a randomized trial. Lancet 1999 354 (9195):2025–8.
5. Zollinger PE, Tuinebreijer WE, Breederveld RS, Kreis RW. Can vitamin C prevent complex regional pain syndrome in patients with wrist fractures? A randomized, controlled, multicenter dose-response study. J Bone Joint Surg Am 2007 89:1424–31.
6. Cazeneuve JF, Leborgne JM, Kermad K, Hassan Y. Vitamin C and prevention of reflex sympathetic dystrophy following surgical management of distal radius fractures. Acta Orthop Belg 2002 68:481–4.
7. Chen JY, Chang CY, Feng PH, Chu CC, So EC, Hu ML. Plasma vitamin C is lower in postherpetic neuralgia patients and administration of vitamin C reduces spontaneous pain but not brush-evoked pain. Clin J Pain. 2009 25(7):562-9. doi: 10.1097/AJP.0b013e318193cf32.
8. Carr AC, McCall C. The role of vitamin C in the treatment of pain: new insights. J Transl Med 2017 15: 77.
Competing interests: No competing interests