Propionyl-L-carnitine (PLC) has some scientific support for use in Raynaud's disease, especially in cases secondary to systemic sclerosis. A few small clinical trials have investigated its efficacy. For example, a randomized, double-blind, placebo-controlled study published in the journal Arthritis & Rheumatism (2002) found that patients with systemic sclerosis-associated Raynaud's phenomenon who took PLC experienced a statistically significant reduction in the frequency, duration, and severity of Raynaud's attacks compared to placebo. The proposed mechanism involves PLC’s ability to improve endothelial function and peripheral blood flow, possibly through enhancement of mitochondrial energy metabolism and nitric oxide-mediated vasodilation.

However, the number of studies is limited, and sample sizes have generally been small. Systematic reviews (e.g., a 2017 Cochrane review) have noted that while PLC and other carnitine derivatives show promise, the quality of evidence is moderate at best due to methodological limitations and risk of bias in existing studies. PLC is not included in current mainstream clinical guidelines for Raynaud's disease, but its use is sometimes considered in refractory cases, particularly when standard therapies fail or are contraindicated. Thus, while there is scientific evidence to support its use, it is not robust or universally accepted.