Acetaminophen for Anxiety

Overseen By Savannah Yerman, M.A.

Age: 18+

Sex: Any

Trial Phase: Academic

Sponsor: University of Guelph

Must not be taking: Blood thinners

Disqualifiers: Liver disease, Kidney disease, Pregnancy, others

Approved in 4 Jurisdictions This treatment is already approved in other countries

Compensation: Varies

Number of Visits: 1

Duration: 1 hour

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial explores how acetaminophen (also known as Tylenol or Panadol) affects fear responses by examining behavior, physical reactions, and self-reported feelings. Participants will take either acetaminophen or a placebo to determine any differences in fear experiences. Ideal candidates are English-speaking adults who have previously taken acetaminophen without issues and have no acetaminophen-related health risks. As an unphased trial, this study allows participants to contribute to scientific understanding of how common medications might influence emotional responses.

Will I have to stop taking my current medications?

The trial does not specify if you need to stop taking your current medications, but you cannot participate if you are taking blood-thinning medications or other products with acetaminophen.

Is there any evidence suggesting that this trial's treatments are likely to be safe?

Research shows that acetaminophen is generally safe when used as directed. Most people can safely take standard doses, but excessive amounts can cause serious liver damage. Mixing it with alcohol increases the risk of liver problems.

Acetaminophen can also cause rare skin reactions. The FDA has suggested adding warnings about this to the drug's label. Overall, when used in typical doses for pain relief and fever, acetaminophen has a strong safety record.

In this study on fear responses, participants will take 1000 mg of acetaminophen, a common dose in many over-the-counter products. Following the recommended dosage is key to minimizing risks. ^{1 2 3 4 5}

Why are researchers excited about this trial?

Most treatments for fear-related conditions focus on therapy or medications targeting neurotransmitters like serotonin. But acetaminophen, commonly known for its role as a pain reliever, is being looked at in a new way. Researchers are excited about acetaminophen because it might alter emotional responses without the side effects typical of antidepressants or anti-anxiety medications. Its potential to influence fear is intriguing and could offer a simpler, more accessible treatment option. Plus, since acetaminophen is already widely used, it has a well-known safety profile.

What evidence suggests that acetaminophen could be effective for fear responses?

Research has shown that acetaminophen can reduce pain, such as that caused by osteoarthritis, a joint disease leading to knee pain and stiffness. It provides short-term pain relief comparable to ibuprofen for this condition. However, acetaminophen is less effective for long-term pain or sudden low back pain, with little evidence supporting its use for ongoing pain. In this trial, participants will receive either acetaminophen or a placebo to investigate its potential effect on fear, though no specific data currently proves its effectiveness for this purpose. ^{6 7 8 9 10}

Who Is on the Research Team?

Pat Barclay, Ph.D.

Principal Investigator

University of Guelph

Are You a Good Fit for This Trial?

Inclusion Criteria

Literate

Does not have any risk factors associated with acetaminophen (history of liver or kidney disease, taking other products with acetaminophen, has any allergies to acetaminophen, taking blood-thinning medications, drinks more than 12 alcoholic drinks per week for females, or more than 15 alcoholic drinks per week for males, are/ could be pregnant)

Has taken acetaminophen in the past without any adverse reactions

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

1-2 weeks

Treatment

Participants receive either 1000 mg acetaminophen or 1000 mg placebo and engage in virtual reality tasks to assess fear responses

1 hour

1 visit (in-person)

Follow-up

Participants are monitored for safety and effectiveness after treatment

1-2 weeks

What Are the Treatments Tested in This Trial?

Interventions

• Acetaminophen
• Placebo

How Is the Trial Designed?

Group I: Acetaminophen Condition Experimental Treatment 1 Intervention

1000 mg acetaminophen

Group II: Placebo Condition Placebo Group 1 Intervention

1000 mg microcrystalline cellulose

Acetaminophen is already approved in United States, European Union, Canada for the following indications:

Approved in United States as Tylenol for:

• Pain relief
• Fever reduction

Approved in European Union as Paracetamol for:

• Pain relief
• Fever reduction

Approved in Canada as Tylenol for:

• Pain relief
• Fever reduction

Who Is Running the Clinical Trial?

University of Guelph

Lead Sponsor

Trials

87

Recruited

15,100+

Natural Sciences and Engineering Research Council, Canada

Collaborator

Trials

63

Recruited

3,000+

Published Research Related to This Trial

Paracetamol, first marketed in the U.K. in 1956, is widely used as an analgesic (pain reliever) and antipyretic (fever reducer).

It has gained popularity among both healthcare professionals and the public as a safer alternative to aspirin for pain and fever management.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Paracetamol. Meredith, TJ., Goulding, R.[2019]

The new fast-dissolving acetaminophen tablet formulation (FD-APAP) disintegrates significantly faster than standard acetaminophen tablets, with a mean disintegration time of 12.9 minutes compared to 69.6 minutes (P < 0.0001).

FD-APAP also shows a quicker absorption rate, with a median time to peak concentration (Tmax) of 0.50 hours versus 0.67 hours for standard acetaminophen (P < 0.01), potentially leading to improved pain relief outcomes.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Comparison of a novel fast-dissolving acetaminophen tablet formulation (FD-APAP) and standard acetaminophen tablets using gamma scintigraphy and pharmacokinetic studies. Wilson, CG., Clarke, CP., Starkey, YY., et al.[2022]

In a study of 57 malaria patients, the combination of Artemisinin-Based Combination Therapies (ACTs) with paracetamol significantly altered 24 out of 37 evaluated toxicity markers, indicating potential safety concerns with this treatment regimen.

The findings suggest that careful selection of ACTs plus paracetamol is crucial, especially for patients with existing health conditions, due to the observed changes in various biochemical and haematological indices.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Toxicological effect of Artemisinin-Based Combination Therapies plus Paracetamol in malaria patients. Aghahowa, SE., Ozolua, RI., Bafor, EE., et al.[2023]

In a study involving 97 children aged 6 to 12 with pharyngotonsillitis, paracetamol syrup was found to be significantly more effective than placebo in reducing pain, as reported by both children and parents.

Both paracetamol and ketoprofen lysine salt were shown to be safe and effective analgesics for treating sore throat in children, with no significant adverse effects reported.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

A randomized, double-blind, placebo-controlled trial of paracetamol and ketoprofren lysine salt for pain control in children with pharyngotonsillitis cared by family pediatricians. Ruperto, N., Carozzino, L., Jamone, R., et al.[2021]

In a survey of 5000 patients, nearly 50% were found to have contraindications for ibuprofen, suggesting that many individuals may not safely use this common over-the-counter pain reliever, while only 6.8% had contraindications for paracetamol.

The findings indicate that the results of the PAIN study, which suggested similar tolerability for ibuprofen and paracetamol, may not apply to the general population, as the study excluded many patients who could be at risk when using ibuprofen without medical supervision.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

A prospective survey to compare the suitability profiles of over-the-counter ibuprofen and paracetamol use in a French general practitioner-controlled population. Pigeon, P., Robillard, E., Clarke, GD., et al.[2018]

Ibuprofen has been shown to be effective for treating acute migraine attacks in children, providing pain relief at 2 hours compared to a placebo, with no significant difference in adverse events reported.

Paracetamol did not demonstrate a significant difference in efficacy compared to placebo, and there was no notable difference in effectiveness between ibuprofen and paracetamol for treating migraines.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Treatment of acute migraine attacks in children with analgesics on the World Health Organization Essential Medicines List: A systematic review and GRADE evidence synthesis. Jeric, M., Surjan, N., Jelicic Kadic, A., et al.[2019]

Citations

1. ncbi.nlm.nih.gov ncbi.nlm.nih.gov/books/NBK482369/

Acetaminophen - StatPearls - NCBI Bookshelf - NIH Although these effects, warnings, and associations have been documented, acetaminophen remains a safe and effective medication when used ...

2. tylenolprofessional.com tylenolprofessional.com/safety-and-efficacy/efficacy

TYLENOL® (Acetaminophen) Efficacy At 4 weeks, acetaminophen was shown to be as effective as ibuprofen for short-term symptomatic treatment of OA pain of the knee.

3. ehjournal.biomedcentral.com ehjournal.biomedcentral.com/articles/10.1186/s12940-025-01208-0

Evaluation of the evidence on acetaminophen use and ... Most results are consistent across different time periods, datasets, and patient populations: when a mother takes acetaminophen while pregnant, ...

4. pubmed.ncbi.nlm.nih.gov pubmed.ncbi.nlm.nih.gov/33786837/

The efficacy and safety of paracetamol for pain relief There is high quality evidence that paracetamol is not effective for relieving acute low back pain (MD, 0.2 points; 95% CI, -0.1 to 0.4 points).

5. onlinelibrary.wiley.com onlinelibrary.wiley.com/doi/10.1111/bcpt.12527

Acetaminophen for Chronic Pain: A Systematic Review on ... In conclusion, there is little evidence to support the efficacy of acetaminophen treatment in patients with chronic pain conditions. Assessment ...

6. sigmaaldrich.com sigmaaldrich.com/CA/fr/sds/sial/a3035?srsltid=AfmBOooxrCh3IMGneCXyAOQJXraQef1Ts_541nqw8t15sl4J3FWzFiAY

SAFETY DATA SHEET OSHA: No component of this product present at levels greater than or equal to 0.1% is on OSHA's list of regulated carcinogens. Reproductive ...

7. fishersci.com fishersci.com/store/msds?partNumber=AC102330050&productDescription=4-ACETAMIDOPHENOL%2C98%25+5GR&vendorId=VN00032119&countryCode=US&language=en

SAFETY DATA SHEET No protective equipment is needed under normal use conditions. Handle in accordance with good industrial hygiene and safety practice. Light ...

8. medline.com medline.com/media/catalog/Docs/MSDS/MSD_SDSD11549.pdf

SAFETY DATA SHEET doses, long-term chronic use or with alcohol, acetaminophen may cause liver damage, acute renal failure and jaundice. Inhalation If symptomatic, move to fresh ...

9. cdn.caymanchem.com cdn.caymanchem.com/cdn/msds/22629m.pdf

Safety Data Sheet 103-90-2 Acetaminophen​​ Oral LD50 2,404 mg/kg (rat) · Primary irritant effect: · on the skin: Irritant to skin and mucous membranes. on the eye: ...

10. fda.gov fda.gov/drugs/information-drug-class/acetaminophen

Acetaminophen Acetaminophen may cause rare but serious skin reactions. In 2024, FDA proposed adding a warning to the label for over-the-counter acetaminophen- ...