L-theanine User Reviews & Ratings (Page 3)

• Dee...
• Taken for less than 1 month
• October 13, 2019

For Dietary Supplementation "Took 100 mg of L-theanine with a 20 oz coffee. Felt energetic and very focused all day long, just like it said I would. Went to sleep and remember having bad nightmares. Woke up at 4 am with the worst gas and diarrhea I ever had (to the point I thought about going to the ER). I do believe they are onto something with this drug, but the way it randomly affects each person completely differently tells me that more research is needed. It is asinine to be sold over the counter."

• Jda...
• Taken for less than 1 month
• October 4, 2019

For Dietary Supplementation "I've been having panic attacks. I researched and saw this was highly recommended. I took 100 mg in the morning. That's it. I only took one. It made me feel calm, then way too hyped up, and my heart started beating very fast. I got all jittery. I panicked because of the fast heartbeats! I thought I was having a heart attack. Never again."

• Jen...
• Taken for 1 to 6 months
• September 5, 2019

"I also struggle with generalized anxiety disorder. It doesn’t usually disrupt my life in such a forceful way, luckily, but it does cause me issues with falling asleep and focusing at work. I tried taking 200 mgs at night and 100 mg in the morning, as suggested by several websites. I did this for almost two months, and I started feeling VERY depressed and had some really dark thoughts. While this does happen occasionally, it’s really usually only anxiety I struggle with. I decided to stop taking it to see what would happen; how could a supplement make me feel this way? Well, within a few days, this depression, borderline crippling dark feeling I had, totally disappeared. I took a month and tried again; smaller dose and tried a tea that also had it and experienced the same thing. Super strange... I think it’s worth a try, but monitor your moods."

• Gen...
• Taken for less than 1 month
• July 11, 2019

For Dietary Supplementation "48-year-old male. Took it for general anxiety disorder, tried every med out there, almost everyone, some worked for a couple of years then stopped working so I go to another, on these meds for 19 years, very medication sensitive, got off all meds a year ago, still had a little anxiety so took l-theanine for about a week, worked really well for 7 days then suddenly developed a massive headache with extreme neck pain and dizziness. I stopped taking l-theanine 250 mgs. It's been 2 days since I stopped and the headache and neck pain are almost gone. Definitely not for me, allergic to pain lol!"

• Sta...
• Taken for 1 to 6 months
• March 19, 2019

For Dietary Supplementation "This raised my amylase and lipase levels to such a high level that my Dr. ordered a CAT scan. Luckily for me, the CAT scan came back fine. I stopped taking the supplement, they redid my blood work two more times after discontinuing this supplement, and my levels started to return to normal, kind of. This scared the crap out of me, that an over-the-counter, supposedly safe medication would do something like that to your pancreas."

• Myl...
• February 18, 2019

For Dietary Supplementation "Honestly, this really isn’t as great as it seems. Yeah, it will do its job and relax you, but to the point you start forgetting stuff. Being in weird moods. Your appetite will be different. Also, my stomach has just been feeling full, and heartburn happens easier than it did before. If I drink a beer or two, it just feels like I’m so full and get a weird feeling. Also, makes you have even worse anxiety after you take it. As if it makes you feel okay, but when it wears off or you don’t take it, you feel crazy. At least I did. I will no longer take this. I don’t recommend it unless you want to feel not like yourself. Don’t let it make you feel this is a thing that doesn’t have side effects because it does."

• Egg...
• Taken for less than 1 month
• October 2, 2018

For Dietary Supplementation "I began taking this about 3 weeks ago, as it had a lot of good reviews and seemed to be helpful for those with anxiety and social anxiety, which I have both of quite badly. I take 200 mg daily, a few times I have doubled it, and only one day did I feel slightly less anxious, and by slightly less, I mean barely any difference. I have not had any good results, it's like I'm not taking anything unless it's too soon to tell."

• dog...
• Taken for 1 to 6 months
• May 31, 2018

For Dietary Supplementation "I don't feel anything or notice any difference from L-theanine."

• Anonymous
• Taken for less than 1 month
• September 29, 2017

For Dietary Supplementation "Took one 200 mg pill with dinner, after an hour, felt relaxed, my neck felt relaxed, tightness gone. However, I had the worst night sleep, woke up several times, and finally at 2:30 a.m., gave up and got out of bed. I definitely had a strange reaction to it. Won't be taking it again."

• She...
• Taken for less than 1 month
• January 12, 2022

For Dietary Supplementation "I took 200 mg about a month ago for a few days to help with anxiety. It seemed to work at first, but then I felt more anxious as it wore off later. I also had a burning feeling in my stomach and reflux. The second day I took it with caffeine/coffee. I was very focused-like a robot, getting things done. The burning continued, even after taking my reflux meds. I again felt anxious when it wore off. Recently, I just took some melatonin and didn’t realize it had 200 mg of l-theanine. I later had cramping and diarrhea. That is not normal at all for me. I also woke up in the night feeling very anxious. I think it’s all from the l-theanine. I would not have taken it recently if I’d known it was in the melatonin. Magnesium works much better for me for calm and sleep, but you have to use the glycinate kind or it can cause gastro issues. I think it could help some people, but the side effects were terrible for me. In fact, it caused anxiety instead of helping it."

• bil...
• Taken for 1 to 6 months
• January 28, 2021

For Dietary Supplementation "I tried this when my doctor recommended it for my chronic insomnia, 100 mg. I find it has the opposite effect. While it relaxes you, it makes your mind very aware and focused, too much so to sleep. I woke many times in the night, and after a few nights, I just didn't sleep. While I did not have rapid heartbeats like many have reported on here, I did have substantially elevated blood pressure about 5 or 6 hours after taking the pill (every time). I'm wondering how many of those reporting pounding heartbeat also had high BP but didn't have a BP reader? I know generally doctors don't love you taking amino acids individually because you're not getting a natural product in a small proportional dose. L-theanine is not something I'd take again. Anything that affects your brain chemistry, you need to be cautious with."

• lau...
• Taken for less than 1 month
• January 5, 2021

For Dietary Supplementation "Took 100 mg of l-theanine and got a headache about two hours later, along with some brain fuzziness. Not entirely miserable, but definitely not desirable. Not sure if I've felt noticeably calmer or more focused."

• Str...
• Taken for less than 1 month
• September 29, 2019

For Dietary Supplementation "At first, I noticed that my anxiety was decreasing while taking this, but as I continued to take it, I got extremely depressed and felt weird (my anxiety came back). My emotions were very scattered, and I don’t know if it was because of this supplement because I heard there’s not supposed to be any side effects. Regardless, I think I’m going to stop taking it."

• Kan...
• Taken for less than 1 month
• July 27, 2019

For Dietary Supplementation "Been taking it for a week and have had very vivid dreams, clenched fists, crying, nightmares every single night. Thought it may have been coincidence, but I think not since that's the only thing I did differently. I think I will just go back to taking my 10 mg of melatonin."

• Anonymous
• Taken for less than 1 month
• February 21, 2018

For Dietary Supplementation "After one dose (100 mg), I had severe chest and abdominal cramping. I tried 2 days later with more severe and more frequent surges of pain. Horrified with side effects that 'are not even noted.'"

• Rom...
• Taken for less than 1 month
• November 25, 2021

For Dietary Supplementation "Started taking 100 mg to help fall asleep, and it worked great, took it about 30 min before bed. But then I began to realize additional muscle fatigue and stopped taking it. As with all supplements, they are trial and error. Did not notice any other side effects."

• Jay...
• Taken for less than 1 month
• November 23, 2021

For Dietary Supplementation "Took 225 mg before bed for several nights in a row (4 or 5 maybe). I did sleep well and had vivid dreams. I noticed my premature atrial contractions that I have had diagnosed previously were especially frequent and bothersome. I have had them now and then my whole life, but they are only frequent and dizzying under periods of extreme stress and fatigue, which I am not experiencing right now. I didn't correlate the two until I found others reporting palpitations. Unfortunately, I haven't taken theanine in a couple of weeks, but the problem persists. Obviously, I can't say for sure it caused the problem, but it is the only change in my routine that I can correlate it with. It hasn't gone away with cessation of the supplement, though. 225 mg is quite a high dose apparently. Be careful and start with 50 mg if you are going to try it."

• BAM...
• Taken for less than 1 month
• January 11, 2019

For Dietary Supplementation "This really does help you be calm and focus, however, it gives me severe insomnia. Even if I take it in the morning, I can't fall asleep that night. It's like my brain is completely wired on it, and what little sleep I got was very restless. If you have insomnia, I would recommend testing this out on a day where you don't need to be up for anything the next morning."

• Jim...
• Taken for 1 to 6 months
• September 14, 2018

For Dietary Supplementation "Every time I use this supplement, I have either an intense dream or a full-blown graphic, bloody nightmare. The night before last, it was about a bloody body being dragged around and hidden in my house! This is a known side effect of this supplement. The other potential benefits, of lowering cortisol and helping me stay asleep, are all great. However, if I feel gross all day remembering the feelings of these dreams, that's not helping me be less stressed or focused during the day."

• Nat...
• Taken for less than 1 month
• August 13, 2018

For Dietary Supplementation "Took this as I was suffering from anxiety and wanted to avoid prescription medication. I took this before bed, felt a little relaxed, and slept well for 3 hours. Woke up after that and could never sleep after. Don't think this is right for me, so gave up."

• Sha...
• February 21, 2017

For Dietary Supplementation "I started taking this about two weeks ago for insomnia. It was combined with lavender oil as a natural sleep aid. It works for helping me to shut my brain off at night and fall asleep, but it caused severe dizzy spells and bad headaches. I also had some stomach upset. I hear that's a rare reaction, but just wanted users to be aware of the possibility. Today I had a dizzy spell so bad in the kitchen that I fell and hurt my hip. I am a 37-year-old woman."

• Pal...
• Taken for less than 1 month
• June 10, 2025

"Glad to read I am not the only one with palpitations. Heart feels like it's pumping harder, so I will have to stop. Too bad because it lowered my blood pressure really well. Haven't read anything like this, but I'm getting a yeast or bread-like smell from it too. I took 100 mg."

• Syl...
• Taken for less than 1 month
• December 26, 2024

For Dietary Supplementation "I started taking L-Theanine for sleep. It worked well, associated with magnesium glycinate and chelate. I could sleep very well, but I started to be depressed and very anxious as soon as I woke up and during the day. I am normally a very happy and active person. So I had to stop taking it, and I went back to my happy mood."

• Amw...
• Taken for less than 1 month
• February 25, 2023

"I am grateful to have come across this website review page. It occurred to me, after experiencing lightheadedness, near-fainting spells, and heart palpitations for the past week and a half, that it could be related to something I was taking. I decided to search for information on L-Theanine, as I had added 50 mg of it to my nightly routine about 3.5 weeks ago to aid in sleeping, which it did. I recently visited the doctor to have an EKG and blood work done to investigate these new symptoms, but everything came back normal. However, I did notice a drop in my blood pressure from its usual 120/80 to 90/70, and my heart rate decreased from the 80s to the 70s. Upon reading the reviews, it appears that my recent issues could be linked to L-Theanine. I appreciate everyone sharing their experiences, as everyone is affected differently by various substances. Although some may benefit, others may not. I am currently grateful and have decided not to take L-Theanine tonight."

• Jac...
• Taken for 1 to 6 months
• October 15, 2021

For Dietary Supplementation "Heart palpitations within 5 minutes of taking 100 mg. This is after about one month of usage without any problems. It was providing me the benefit of a clear head, no fogginess when waking up, but the palpitations are concerning and affect sleep quality. Will try to reduce the dosage to 50 mg."