How commonly was ivermectin prescribed by doctors for humans prior to 2020?
Prior to 2020, ivermectin was regularly prescribed for humans but primarily in specific contexts:
In the United States and other developed countries, ivermectin was prescribed relatively infrequently, mainly for:
- Strongyloidiasis (intestinal threadworm infection)
- Scabies (particularly for severe or treatment-resistant cases)
- Head lice (usually as a second-line treatment)
- Rosacea (in topical form as Soolantra/Rosiver)
In contrast, ivermectin was much more widely used in tropical and developing regions where parasitic diseases are endemic. In these areas, it was commonly distributed through mass drug administration programs to combat:
- River blindness (onchocerciasis)
- Lymphatic filariasis
- Other parasitic diseases
The Mectizan Donation Program, established in 1987, has provided billions of treatments in endemic countries, particularly across Africa and parts of Latin America and Asia.
Annual global usage is difficult to quantify precisely, but prior to 2020, hundreds of millions of ivermectin doses were administered annually worldwide, with the vast majority being in mass treatment programs rather than individual prescriptions.
Before 2020, ivermectin was prescribed relatively infrequently for humans in the United States and other developed countries. Its primary use was for treating specific parasitic infections, such as onchocerciasis (river blindness) and intestinal strongyloidiasis, which are more common in tropical regions. In these areas, ivermectin played a significant role in public health programs aimed at controlling parasitic diseases.
In developed countries, prescriptions were limited to cases involving travel-related infections or specific conditions like head lice and rosacea, for which it is also approved. Its use was far less widespread compared to its veterinary applications.
Key Summary: Prior to 2020, ivermectin had limited but important medical use in humans, primarily for specific parasitic infections through both clinical prescriptions and mass drug administration programs.
1. Primary Medical Uses (Pre-2020)
- Onchocerciasis (River Blindness):
- Core treatment in WHO elimination programs (annual/biannual dosing)
- Over 4 billion doses donated through Merck's Mectizan program (1987-2020)
- Strongyloidiasis:
- First-line treatment for this persistent intestinal worm infection
- Particularly important for immunocompromised patients
- Other Parasitic Infections:
- Alternative treatment for scabies (especially crusted scabies)
- Occasional use for lymphatic filariasis (with albendazole)
2. Prescription Frequency
| Setting | Usage Pattern | Estimated Annual Prescriptions (Global) |
|---|---|---|
| Clinical Practice | Individual prescriptions | ~1-2 million (mainly for strongyloidiasis) |
| Mass Drug Administration | Community-wide distribution | ~250-300 million doses (for onchocerciasis control) |
3. Geographic Distribution
- High-Prescription Regions:
- Sub-Saharan Africa (onchocerciasis endemic areas)
- Latin America (parts of Brazil, Venezuela, etc.)
- Southeast Asia (strongyloidiasis-prevalent areas)
- Low-Prescription Regions:
- North America/Europe (mainly for travelers/migrants with parasitic infections)
- Non-endemic countries (rare use except for specialized cases)
4. Prescription Trends Over Time
- 1987-2000: Rapid adoption for onchocerciasis control
- 2000-2015: Expanded use for strongyloidiasis (especially in HIV/AIDS patients)
- 2015-2020: Stable prescription rates with slight increase for scabies outbreaks
Note: The COVID-19 pandemic (2020 onward) dramatically altered prescription patterns, but pre-2020 use was narrowly focused on parasitic diseases with strong evidence bases.
Prior to 2020, ivermectin was primarily prescribed by doctors for its approved uses in treating parasitic infections. These included:
- Onchocerciasis (river blindness): Especially in mass drug administration programs in endemic regions.
- Strongyloidiasis: Considered the drug of choice by the WHO for this condition.
- Lymphatic filariasis: Often as part of mass drug administration, particularly in areas where onchocerciasis is also present.
- Other helminth infections: Such as ascariasis, trichuriasis, and hookworm infections, though other drugs like albendazole or mebendazole might have been preferred first-line treatments in some cases.
- Scabies: Both oral and topical formulations were used.
- Head lice: Oral ivermectin was an option.
- Rosacea and Blepharitis: Topical ivermectin formulations were available for these conditions.
How commonly it was prescribed overall is difficult to quantify precisely without specific prescription data from before 2020. However, several points can help understand its usage:
- Relatively low overall prescription numbers in the US: One study indicated that before the pandemic (March 2019 - March 2020), there were approximately 3,600 outpatient retail prescriptions for ivermectin per week in the US. This suggests that while routinely used for its approved indications, it wasn't among the most commonly prescribed drugs overall.
- Mass drug administration in endemic countries: In regions with prevalent parasitic diseases like onchocerciasis and lymphatic filariasis, ivermectin was distributed widely and frequently as part of public health campaigns. This constituted a significant portion of its global usage.
- Specialized use: Prescriptions in non-endemic countries like the US were mainly handled by specialists in infectious diseases, dermatologists (for scabies and rosacea), and general practitioners who encountered these specific conditions.
- Stable prescription rates before the pandemic: Data from the US military health system showed stable annual prescription rates for ivermectin from 2017 through 2020.
It's important to note that off-label prescribing (using a drug for a condition it's not officially approved for) did occur before 2020, but the extent of this for ivermectin is not well-documented. Some in-vitro studies had suggested potential antiviral activity against certain viruses before the COVID-19 pandemic, but these did not typically translate to widespread off-label use in humans.
The significant increase in ivermectin prescriptions occurred primarily during the COVID-19 pandemic, driven by claims of its effectiveness against the virus, despite a lack of robust scientific evidence and warnings from health authorities. This surge was a notable deviation from its pre-2020 usage patterns.
Before 2020, ivermectin was prescribed relatively infrequently for humans — but it was an important and established drug in specific medical areas.
| Context | Details |
|---|---|
| Common Uses |
Mainly for parasitic infections like:
|
| Prescription Volume |
|
| Public Awareness |
|
Summary
Before the pandemic, ivermectin was not a drug most doctors wrote prescriptions for regularly — unless they were treating a narrow set of tropical or parasitic diseases.
It was essential in specific areas of medicine but not widely used like antibiotics or blood pressure medications.
Before 2020, ivermectin was prescribed for humans primarily to treat parasitic infections such as onchocerciasis (river blindness), strongyloidiasis, scabies, and head lice. Its use was well-established in specific contexts, particularly in regions with high prevalence of parasitic diseases, but it was not among the most frequently prescribed medications in general medical practice.
Prescription Frequency in the United States
- Annual Prescriptions: According to data from the ClinCalc DrugStats Database, ivermectin was the 314th most commonly prescribed medication in the United States in 2022, with approximately 200,000 prescriptions annually. Pre-2020 prescription numbers were lower, with a reported weekly average of about 3,600 prescriptions (approximately 187,200 annually) during the period from March 2019 to March 2020, based on CDC data from the IQVIA National Prescription Audit.
- Monthly Average: A 2021 analysis by Komodo Health reported an average of 39,864 prescriptions per month in 2019, equating to roughly 478,368 prescriptions annually. This suggests ivermectin was prescribed modestly compared to more common drugs like antibiotics or statins.
Global Context
- Mass Drug Administration (MDA): Globally, ivermectin was widely used in MDA campaigns, particularly in Africa, Latin America, and Yemen, for onchocerciasis and lymphatic filariasis. Approximately 80–90 million people received ivermectin annually through these programs, with over 300 million total treatments approved for lymphatic filariasis by 2011. These treatments were typically administered under public health initiatives rather than individual prescriptions.
- Tropical and Developing Regions: In areas with high parasitic disease burdens, ivermectin was a cornerstone treatment, often distributed free through donation programs like Merck’s Mectizan program. Its use was less common in developed nations where parasitic infections are rare.
Clinical Use
- Approved Indications: Ivermectin was FDA-approved for human use since 1987 for conditions like strongyloidiasis and onchocerciasis, with topical formulations later approved for head lice and rosacea. Prescriptions were typically issued by infectious disease specialists, dermatologists, or primary care physicians in areas with relevant patient populations.
- Off-Label Use: Some physicians prescribed ivermectin off-label for other parasitic infections (e.g., cutaneous larva migrans, Mansonella ozzardi) or in combination with albendazole for soil-transmitted helminths, but this was not widespread in routine practice.
Comparison to Post-2020 Trends
Pre-2020, ivermectin prescriptions were stable and relatively low in the U.S., reflecting its niche role in treating parasitic infections. The significant increase in prescriptions during the COVID-19 pandemic (e.g., peaking at 88,000 per week in August 2021) was driven by unapproved use for COVID-19, leading to a 24-fold increase over pre-pandemic levels. This contrasts sharply with its more limited, targeted use before 2020.
Limitations and Notes
- Exact prescription numbers before 2020 vary by source due to differences in data collection (e.g., retail pharmacies vs. public health programs). The Komodo Health estimate (39,864/month) is higher than the CDC’s (3,600/week), possibly reflecting broader data inclusion.
- In the U.S., ivermectin was less common than in tropical regions, where MDA programs drove higher usage. Anecdotal reports from physicians on X suggest it was prescribed regularly for parasitic infections like strongyloidiasis without controversy before COVID-19.
- Data on off-label prescriptions pre-2020 is sparse, making it hard to quantify non-standard uses.
In summary, ivermectin was prescribed moderately in the U.S. (hundreds of thousands annually) and extensively in global public health campaigns (millions annually) before 2020, primarily for parasitic infections. Its prescription frequency was low compared to common medications but significant in specific medical and geographic contexts. Always consult a healthcare provider for medical advice regarding ivermectin use.
Prior to 2020, ivermectin was prescribed for humans primarily as an antiparasitic medication, with stable prescription rates observed in the years leading up to the COVID-19 pandemic. Key findings include:
Pre-pandemic prescription trends
- Average monthly prescriptions: In 2019, a monthly average of 39,864 ivermectin prescriptions were filled in the U.S., according to pharmacy claims data.
- Annual military prescription rates: Among U.S. military members, annual ivermectin prescription rates remained stable from 2017 through 2020, ranging between 22.7 and 27.2 prescriptions per 100,000 person-years.
- Common uses: Approved for parasitic infections like scabies, river blindness, and strongyloidiasis, ivermectin had been safely used for decades, with over 3 billion doses administered globally by 2022.
The drug saw a dramatic increase in off-label use for COVID-19 starting in late 2020, but prior to this, its use remained consistent with its established antiparasitic applications.