What are the potential side effects of applying ivermectin horse paste on human skin?

1. How people describe the harms — vivid patient reports that matter

Multiple patient reports and forum summaries describe burning, itching, redness, rashes, dry flaky skin, scabbing and prolonged flares after applying equine ivermectin preparations to the face; some users reported severe joint pain localized to fingers and toes and worsening rosacea with bleeding and scabbing ^[1]. These anecdotal accounts are consistent across community discussions and a small survey of patients considering topical equine ivermectin for rosacea, highlighting that real-world misuse produced visible and painful skin outcomes even when data are not from randomized trials ^{[4] [5]}. The presence of flavorings, sugars, salts and other excipients in veterinary pastes creates an additional risk of chemical irritation on delicate facial skin ^{[1] [5]}.

2. What regulators and public-health agencies say — clear warnings and clinical risks

State health departments and the FDA have warned against ingesting or misusing livestock ivermectin; these warnings extend to non‑authorized topical uses given the unknown pharmacokinetics and overdose risk from high‑concentration veterinary formulations ^[2]. Documented systemic side effects linked to ivermectin misuse include gastrointestinal symptoms, neurological disturbances (dizziness, confusion, seizures), severe hepatitis and, in extreme cases, coma or death when taken in large amounts or in inappropriate formulations ^{[2] [6]}. Those official advisories stress medical supervision and use of FDA‑approved human formulations where clinically indicated, underscoring that veterinary products bypass human safety testing and labeling ^[2].

3. Pharmacology and formulation differences — why horse paste is not the same as Soolantra

Veterinary ivermectin pastes typically contain higher concentrations (commonly about 1.87%) and include inactive ingredients not evaluated for human dermal safety; by contrast, FDA‑approved topical ivermectin for rosacea (Soolantra) is a 1% formulation tested for human skin ^[5]. The higher drug load and non‑human excipients mean more drug delivery, more irritants, and unpredictable systemic absorption if applied to broken or inflamed facial skin. Medical literature and reviews note ivermectin’s antiparasitic and anti‑inflammatory actions but emphasize that efficacy and safety depend on formulation, dose and route — parameters not met by repurposing veterinary pastes ^{[7] [3]}.

4. Range of likely side effects — from mild irritation to serious systemic harm

Collated reporting and clinical summaries identify a spectrum of adverse events: local skin reactions (burning, stinging, rash, dryness, swelling), allergic responses, and systemic symptoms such as nausea, diarrhea, headache, dizziness and muscle aches; severe cases include eye pain, hepatotoxicity and neurological compromise (confusion, seizures, respiratory distress) when systemic exposure is substantial ^{[6] [3]}. Because veterinary pastes are not dosed for humans, even topical use can lead to unpredictable systemic exposure, particularly if applied to large areas or to skin with increased permeability from inflammation or excoriation ^{[1] [3]}.

5. Evidence gaps and competing narratives — why uncertainty persists

Published surveys and case summaries document patient experiences but randomized clinical trials of equine ivermectin on human skin do not exist; therefore evidence is anecdotal and mechanistic rather than trial‑proven ^{[4] [3]}. Proponents arguing anecdotal benefit point to ivermectin’s anti‑inflammatory potential, and some users claim improvement, but these claims conflict with regulatory cautions and reports of harm. The result is a polarized picture: some individuals report benefit while public-health bodies warn of real danger, and clinical judgment must weigh the lack of human safety data for veterinary formulations ^{[5] [7]}.

6. Practical takeaway — what clinicians and consumers should do right now

Do not use veterinary ivermectin pastes on human skin. Seek evaluation from a licensed clinician for rosacea or other skin conditions and consider FDA‑approved topical ivermectin or alternative, evidence‑based therapies when appropriate. If exposure or adverse effects occur after using a veterinary product, contact poison control or emergency services and inform your clinician about the specific product used, because non‑human excipients and higher concentrations change both local and systemic risk profiles ^{[1] [2] [3]}.