Complex Regional Pain Syndrome type 1 is a pain syndrome that develops after a trauma, surgery, or idiopathically. The incidence after distal radius varies significantly in the literature. There are known contributing factors, such as the female sex but no effective treatment or prophylactic method. This study aims to investigate vitamin C's efficacy in preventing CRPS type 1 following distal radius fractures, as the literature states that it might play a role in prophylaxis.

Complex regional pain syndrome is the most challenging complication to overcome following distal radius fractures. The precise etiology still needs to be fully understood. It is thought that ways of prevention could be the most effective way of managing this dilemma, as no effective treatment is yet to be found.

One of the ways of prevention is vitamin C supplementation, as it is thought that the toxic oxygen radicals play a significant role in the inflammatory process that ultimately manifests as CRPS. Vitamin C, as an antioxidant, could play a role in stopping this process.

The theoretical background of this research is that CRPS commonly occurs following distal radius fractures, and vitamin C supplementation could play a role in prophylaxis. To assess that, the investigator is conducting a randomized controlled trial.

The trial is designed as a multicenter, randomized, controlled study. Two hospitals in Syria, Damascus, participated in this study using the same experimental design.

Adults (18 years or above) with distal radius fractures who will be seen in the emergency department of each hospital will be asked to participate in this study. Patients will be asked to start the trial medication on the day of the fracture following the suitable treatment method chosen by the orthopedics consultant in each hospital. Capsules had to be taken once daily for 90 days. Patients will be allocated randomly to receive either a placebo or 1g of vitamin C daily.

The study's endpoint will be defined as the presence of CRPS at any moment up to one year after the fracture. All participants and physicians will be unaware of the treatment allocation.

The diagnosis will be built upon the Budapest criteria, which will be checked in every follow-up for one year.

Patients will be seen after two weeks, four weeks (or when the cast was removed), six weeks, 12 weeks, six months, and 12 months. The protocol will not compromise the adequate fracture treatment, either conservative or operative, by closed reduction and percutaneous pinning. If necessary, patients will be seen more often and at other times than planned.

Inclusion Criteria:

• participants who were injured with distal radius fractures and classified using the AO classification as A1, A2, A3, B1, and C1.

Exclusion Criteria:

• Multiple trauma patients.
• patients who have neurovascular injuries.
• Patients with fractures are classified using the AO classification as B2, B3, C2, and C3.
• Patients who are eligible for open reduction internal fixation of their fractures.
• Patients with chronic or acute renal failure.
• Patients who already take multi-vitamin supplementation or vitamin C supplementation.

All participants and the consultants making definite treatment decisions and the researcher assistant collecting participants' data will be unaware of allocation until the completion of the study.