What the label lists and what reports show
Imiquimod side effects
Imiquimod's FDA label: “Most common adverse reactions (≥4%) are local skin reactions (erythema, scabbing/crusting, flaking/scaling/dryness, edema, erosion/ulceration, exudate), headache, application site pain, application site irritation, application site pruritus, fatigue …” FAERS holds 2,292 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is erythema (183 reports).
- Generic listed
Check it at the source: the imiquimod FDA label on DailyMed (effective May 23, 2025, Bausch Health US, LLC); the FDA FAERS public dashboard.
What does the patient leaflet say about side effects?
From the patient leaflet: What are the possible side effects of ZYCLARA Cream?ZYCLARA Cream may cause serious side effects, including: • Treatment site skin reactions. Skin reactions including drainage (weeping) or breakdown of the outer layer of your skin (erosion) can happen after a few applications of ZYCLARA Cream. Swelling outside of the vagina (vulvar swelling) may happen in females. Females should take special care if applying the cream at the opening of the vagina because skin reactions can cause pain or swelling, and may cause problems passing urine. If you get skin reactions, wash the treated area with mild soap and water. • Stop ZYCLARA Cream right away and call your healthcare provider if you get any skin reactions that affect your daily activities, or that do not go away. • Flu-like symptoms. Tell your healthcare provider if you get tiredness, nausea, vomiting, fever, chills, muscle pain, and joint pain. […]
Source: FDA drug label, Bausch Health US, LLC, effective May 23, 2025 (SPL set 28cd9b5b-680b-480f-b33d-9c5b52bbf03d), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsMost common adverse reactions (≥4%) are local skin reactions (erythema, scabbing/crusting, flaking/scaling/dryness, edema, erosion/ulceration, exudate), headache, application site pain, application site irritation, application site pruritus, fatigue, influenza-like illness, and nausea.
Table 1: Selected Adverse Reactions Occurring in ≥2% of ZYCLARA-Treated Subjects with AK and at a Greater Frequency than Vehicle in Studies AK1 and AK2
| Adverse Reaction | ZYCLARA, 3.75% (N=160) | ZYCLARA, 2.5% (N=160) | Vehicle (N=159) |
|---|---|---|---|
| Headache | 10 (6%) | 3 (2%) | 5 (3%) |
| Application site pruritus | 7 (4%) | 6 (4%) | 1 (<1%) |
| Fatigue | 7 (4%) | 2 (1%) | 0 |
| Nausea | 6 (4%) | 1 (1%) | 2 (1%) |
| Application site irritation | 5 (3%) | 4 (3%) | 0 |
| Application site pain | 5 (3%) | 2 (1%) | 0 |
| Pyrexia | 5 (3%) | 0 | 0 |
| Anorexia | 4 (3%) | 0 | 0 |
| Dizziness | 4 (3%) | 1 (<1%) | 0 |
| Herpes simplex | 4 (3%) | 0 | 1 (<1%) |
| Lymphadenopathy | 3 (2%) | 4 (3%) | 0 |
| Diarrhea | 3 (2%) | 2 (1%) | 0 |
| Arthralgia | 2 (1%) | 4 (3%) | 0 |
| Influenza like illness | 1 (<1%) | 6 (4%) | 0 |
| Oral herpes | 0 | 4 (3%) | 0 |
| Cheilitis | 0 | 3 (2%) | 0 |
Rows and numbers as the label prints them, under its own column headings (the first rows of a longer table where it runs on). A reaction in a trial table is not necessarily caused by the medicine, and trials differ from everyday use.
From the label: adverse reactions, continuedThe following clinically significant adverse reactions are described elsewhere in the labeling: • Local Skin Reactions [see Warnings and Precautions (5.1) ] • Systemic Reactions [see Warnings and Precautions (5.2) ] Most common adverse reactions (≥4%) are local skin reactions (erythema, scabbing/crusting, flaking/scaling/dryness, edema, erosion/ulceration, exudate), headache, application site pain, application site irritation, application site pruritus, fatigue, influenza-like illness, and nausea. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Bausch Health US, LLC at 1-800-321-4576 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. Actinic Keratosis The data described below reflect exposure to ZYCLARA or vehicle in 479 subjects with AK enrolled in two double-blind, vehicle-controlled trials (Studies AK1 and AK2) [ Clinical Studies (14.1 )]. Subjects applied up to two packets of ZYCLARA, 3.75%, ZYCLARA, 2.5%, or vehicle once daily, to the skin of the affected area (either entire face or balding scalp) for two 2-week treatment cycles separated by a 2-week no treatment period. …
Source: FDA drug label, Bausch Health US, LLC, effective May 23, 2025 (SPL set 28cd9b5b-680b-480f-b33d-9c5b52bbf03d), via openFDA; the full label on DailyMed
What do FAERS reports show?
2,292 reports list imiquimod among the medicines taken, each a report of something that happened, not proof the medicine caused it; 73 are coded as a death and 322 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Of the 20 reactions below, 13 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.
Reports received each year
The 25 most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms
What next?
- Imiquimod: the full record
- label, generics, price, shortages, recalls
- Report a side effect to the FDA
- MedWatch
- Side effects hub
- the most reported medicines and reactions