What is the more likely cause of cheilitis on the upper lip, the platelet-rich plasma (PRP) injection or topical ivermectin (antiparasitic medication)?

From the Guidelines

The topical ivermectin is more likely to have caused the cheilitis than the PRP injection. Platelet-rich plasma (PRP) injections generally have a good safety profile with minimal side effects, typically limited to temporary swelling, bruising, or pain at the injection site, as reported in a recent study 1. In contrast, topical ivermectin is known to occasionally cause skin irritation, including redness, burning, and inflammation, particularly when applied to sensitive areas like the lips. Cheilitis, which is inflammation of the lips characterized by redness, swelling, and sometimes cracking or peeling, is a recognized potential side effect of topical medications, similar to those reported with acitretin use 1. The timing of both interventions on the same day makes it difficult to definitively determine causality, but the mechanism of action of topical ivermectin as a chemical agent applied directly to the skin makes it the more probable culprit.

Some key points to consider:

• PRP injections have been shown to be safe and effective for lip rejuvenation, with minimal side effects 1
• Topical ivermectin can cause skin irritation, including cheilitis, especially when applied to sensitive areas like the lips
• The patient's recent use of topical ivermectin on the same day as the PRP injection makes it more likely that the ivermectin caused the cheilitis
• If the patient needs to continue ivermectin treatment, they should consider temporarily discontinuing application near the lips, using a reduced concentration, or applying less frequently until the cheilitis resolves.

From the Research

Possible Causes of Cheilitis

• The patient had a recent PRP injection to the lips on the same day that they started topical ivermectin, and developed cheilitis on the upper lip.
• There is no direct evidence in the provided studies to suggest that PRP injections can cause cheilitis.
• Topical ivermectin has been reported to cause mild-moderate desquamation, stinging, and burning in some patients 2.
• These side effects are more likely to be related to the development of cheilitis, especially since the patient started using topical ivermectin on the same day.

Comparison of Possible Causes

• The studies provided do not mention PRP injections as a cause of cheilitis.
• Topical ivermectin has been shown to be well-tolerated, but with some adverse events such as desquamation, stinging, and burning 2, 3.
• Based on the available evidence, it is more likely that the topical ivermectin caused the cheilitis, rather than the PRP injection.

Evidence for Topical Ivermectin as a Cause

• A study on the clinical applications of topical ivermectin in dermatology mentions its potential anti-inflammatory properties, but also notes that it can cause side effects such as desquamation and stinging 4.
• Another study on the efficacy and safety of topical ivermectin in patients with uncomplicated scabies reports that topical ivermectin can cause mild-moderate desquamation, stinging, and burning 3.
• These studies suggest that topical ivermectin can cause skin irritation, which may be related to the development of cheilitis 2, 4, 3.