Theanine and Fatigue - a phase IV clinical study of FDA data

Summary:

Fatigue is reported as a side effect among people who take Theanine (theanine), especially for people who are female, 30-39 old, have been taking the drug for 2 - 5 years also take Vitamin D3, and have Narcolepsy.

The phase IV clinical study analyzes which people have Fatigue when taking Theanine. It is created by eHealthMe based on reports of 564 people who have side effects when taking Theanine from the FDA, and is updated regularly.

What is Theanine?

Theanine has active ingredients of theanine. It is often used in insomnia. eHealthMe is studying from 893 Theanine users. Check the latest studies of Theanine.

What is Fatigue?

Fatigue (feeling of tiredness) is found to be associated with 4,027 drugs and 6,382 conditions by eHealthMe. Check the latest studies of Fatigue.

eHealthMe: drug outcomes in the real world

eHealthMe runs one of the largest post-marketing drug safety studies in the world. We study millions of patients and 5,000 more each day. Our data-driven phase IV clinical trials have been referenced on 800+ peer-reviewed medical publications including The Lancet, Mayo Clinic Proceedings, and Nature. Tools to study our phase IV findings are available to the public, anonymous and free >>>.

On Aug, 23, 2026

564 people reported to have side effects when taking Theanine.
Among them, 66 people (11.7%) have Fatigue.

Among these 66 people:

How long have people been on Theanine when they have Fatigue? *

What is the gender of people who have Fatigue when taking Theanine? *

female: 89.39 %
male: 10.61 %

What is the age of people who have Fatigue when taking Theanine? *

What are other drugs people take besides Theanine? *

What are other side effects people have besides Fatigue? *

Dizziness: 31 people, 46.97%
Stress And Anxiety: 28 people, 42.42%
Pain: 22 people, 33.33%
Headache (pain in head): 19 people, 28.79%
Malaise (a feeling of general discomfort or uneasiness): 18 people, 27.27%
Oropharyngeal Pain: 18 people, 27.27%
Nausea (feeling of having an urge to vomit): 18 people, 27.27%
Feeling Abnormal: 16 people, 24.24%
Fall: 15 people, 22.73%
Memory Loss: 14 people, 21.21%

What are the existing conditions these people have? *

Narcolepsy (brain's inability to regulate sleep-wake cycles normally): 22 people, 33.33%
Cataplexy (loss of muscle tone accompanied by full conscious awareness): 17 people, 25.76%
Primary Immunodeficiency Syndrome: 9 people, 13.64%
Immunodeficiency: 6 people, 9.09%
Multiple Sclerosis (a nervous system disease that affects your brain and spinal cord. it damages the myelin sheath): 4 people, 6.06%
Immunodeficiency Common Variable: 4 people, 6.06%
Pain: 3 people, 4.55%
Attention Deficit Hyperactivity Disorder (a chronic condition including attention difficulty, hyperactivity, and impulsiveness): 3 people, 4.55%
Stress And Anxiety: 3 people, 4.55%
Renal Disorder (kidney disease): 2 people, 3.03%

* Approximation only. Some reports may have incomplete information.

Do you take Theanine and have Fatigue?

- Check whether Fatigue is associated with a drug or a condition
- Predict drug outcomes for up to one year with AI
- Get an AI agent to monitor your drugs continuously

Related studies:

Effectiveness of, long term effects of, and alternative drugs to Theanine:

Theanine (893 reports)

Fatigue treatments and more:

Fatigue (967,539 reports)

Browse all side effects of Theanine:

a b c d e f g h i j k l m n o p q r s t u v w x y z

Browse all the drugs that are associated with Fatigue:

Fatigue (4,027 drugs)

Browse all the conditions that are associated with Fatigue:

Fatigue (6,382 conditions)

Related publications that referenced our studies

Peel MM, Cooke M, Lewis-Peel HJ, Lea RA, Moyle W, "A randomized controlled trial of coenzyme Q 10 for fatigue in the late-onset sequelae of poliomyelitis", Complementary therapies in medicine, 2015 Dec .
Peel MM, Cooke M, Lewis-Peel HJ, Lea RA, Moyle W, "A randomized controlled trial of coenzyme Q 10 for fatigue in the late-onset sequelae of poliomyelitis", Complementary therapies in medicine, 2015 Dec .

How the study uses the data?

The study uses data from the FDA. It is based on theanine (the active ingredients of Theanine) and Theanine (the brand name). Other drugs that have the same active ingredients (e.g. generic drugs) are not considered. Dosage of drugs is not considered in the study.

How to use the study?

DO NOT STOP MEDICATIONS without first consulting your doctor. If there are any serious or long term adverse effects discovered in the study, discuss the study with your doctor to ensure that proper medication management will be in place if applicable.

Who is eHealthMe?

With medical big data and proven AI/ML algorithms, eHealthMe provides a platform for everyone to run phase IV clinical trials. We study millions of patients and 5,000 more each day. Results of our real-world drug study have been referenced on 800+ peer-reviewed medical publications, including The Lancet, Mayo Clinic Proceedings, and Nature. Our analysis results are available to researchers, health care professionals, patients (testimonials), and software developers (open API).

WARNING, DISCLAIMER, USE FOR PUBLICATION

WARNING: Please DO NOT STOP MEDICATIONS without first consulting a physician since doing so could be hazardous to your health.

DISCLAIMER: All material available on eHealthMe.com is for informational purposes only, and is not a substitute for medical advice, diagnosis, or treatment provided by a qualified healthcare provider. All information is observation-only. Our phase IV clinical studies alone cannot establish cause-effect relationship. Different individuals may respond to medication in different ways. Every effort has been made to ensure that all information is accurate, up-to-date, and complete, but no guarantee is made to that effect. The use of the eHealthMe site and its content is at your own risk.

If you use this eHealthMe study on publication, please acknowledge it with a citation: study title, URL, accessed date.