Question explored with the scientific record
Conversation so far
- 1 was the covid vaccine harmful?
- 2 would the drug ivermectn have had less side effects if people were able to use it?
Answered on this page ↓
would the drug ivermectn have had less side effects if people were able to use it?
The short version: ivermectin has real, documented side effects that are not trivial, but the evidence does not allow a direct head-to-head comparison with COVID-19 vaccine harms because the studies were never designed that way.
The question asks whether ivermectin would have had fewer side effects than the COVID-19 vaccines if it had been widely used. The honest answer is that the evidence does not settle this. The side effects of ivermectin are real. A pharmacovigilance study of 517 reports found that systemic ivermectin was associated with a threefold higher reporting odds ratio for severe cutaneous adverse reactions (SCARs) and a sevenfold higher odds for toxidermias like Stevens-Johnson syndrome [1]. Of those SCAR cases, 20% resulted in death and 48% in hospitalization [1]. A separate case series of 28 serious neurological adverse events after ivermectin use for non-onchocerciasis indications found three cases with recurrence on rechallenge, supporting a causative role [2]. One fatal case had ivermectin detected in brain tissue at autopsy [2]. These are not mild side effects.
But the comparison is unfair in both directions. The ivermectin safety data comes from passive surveillance systems (FAERS, VigiBase) that detect signals but cannot calculate true incidence rates. The COVID-19 vaccine safety data comes from large active surveillance cohorts that can measure incidence precisely. The vaccine evidence shows myocarditis rates of 28-147 per million in young males [3, 5], which is a known, quantified risk. The ivermectin evidence shows rare but serious events without a reliable denominator. What is clear is that ivermectin is not a harmless drug. It crosses the blood-brain barrier via P-glycoprotein inhibition [4], and its safety profile in the doses proposed for COVID-19 (often much higher than the approved 200 mcg/kg for parasites) was never properly studied in large randomized trials with hard clinical endpoints.
| Adverse Event | Ivermectin (from passive surveillance) | COVID-19 mRNA Vaccines (from active surveillance) |
|---|---|---|
| Severe skin reactions (SCARs) | 3.34x higher reporting odds [1] | Not a known signal |
| Neurological events | 28 serious cases, 3 positive rechallenge [2] | Not a known signal |
| Myocarditis | Not documented | 28-147 per million in young males [3, 5] |
| Deaths in reported cases | 20% of SCAR cases [1] | Very rare, documented |
My call: the evidence does not support the claim that ivermectin would have had fewer side effects than the COVID-19 vaccines. Both have real, documented harms. The ivermectin harms are less well-quantified because the studies were never done at scale, and the COVID-19 vaccine harms are better measured because they were studied in millions of people. Confidence: moderate.
Sources used 5
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Severe cutaneous adverse reactions associated with systemic ivermectin: A pharmacovigilance analysis
Systemic ivermectin was significantly associated with increased reporting of severe cutaneous adverse reactions (SCARs) in FAERS, especially toxidermias, though causality cannot be ascertained.
DOI: 10.1111/1346-8138.16398 -
Serious Neurological Adverse Events after Ivermectin—Do They Occur beyond the Indication of Onchocerciasis?
Serious neurological adverse events were reported in 28 VigiBase cases taking ivermectin for non-onchocerciasis indications, including three with recurrence on rechallenge, suggesting a possible rare causative role beyond onchocerciasis and loiasis.
DOI: 10.4269/ajtmh.17-0042 -
Control of bancroftian filariasis in an endemic area of Polynesia by ivermectin 400 μg/kg
A field trial in Opoa, French Polynesia, shows that semi-annual mass treatment with ivermectin at 400 μg/kg over three rounds markedly reduces bancroftian filariasis prevalence (from 21% to 7%) and microfilariae levels (GMM down to 0.5% of baseline), with high safety and complia…
DOI: 10.1016/s0035-9203(96)90439-3 -
The perils of P-glycoprotein inhibition
A critical review of how P-glycoprotein (MDR1/mdr1) governs drug transport and tissue distribution, highlighting mouse knockout data and clinical implications of MDR1 inhibition for chemotherapy and hepatic/renal drug handling.
DOI: 10.1053/jhep.1996.v24.ajhep0240276 -
Incidence, risk factors, natural history, and hypothesised mechanisms of myocarditis and pericarditis following covid-19 vaccination: living evidence syntheses and review
This living systematic review found that myocarditis after mRNA COVID-19 vaccination occurs most frequently in male adolescents and young adults, with moderate-certainty evidence that Moderna is associated with higher incidence than Pfizer in 18-29 year olds and low-certainty ev…
DOI: 10.1136/bmj-2021-069445