L-theanine User Reviews & Ratings

• Mic...
• Taken for less than 1 month
• June 30, 2022

For Dietary Supplementation "After reading the reviews, I ordered a bottle of 200 mg l-theanine capsules for anxiety, and I just took one early this morning. I didn't read anything about it needing time to take effect, but it's been about 5 hours now, and I don't feel less anxiety at all. I also don't feel productive or clarity of mind, I feel my usual burnout and chaotic mind. I just have this weird feeling in my head like the beginning of what might later be a headache, so I took some ibuprofen to avoid that. I took this capsule specifically today because I'm having irritability and a hard time functioning and getting things done. I guess if you didn't have a bunch of demanding and inconsolable children you're caring for, then this may feel like it works. Has anyone tested this with kids screaming and yelling in the background and constantly asking for things and being dissatisfied? I doubt it. I'm also having back pain from tensing up, but that might just be my anxiety."

• Jen...
• Taken for less than 1 month
• April 5, 2022

For Dietary Supplementation "I am an 18-year-old female, and I have tried the l-theanine and caffeine combination many times to help with my ADHD and mild anxiety, but it has zero effect on me, whether I take it on an empty stomach or not. I tried upping the dose, still, no results."

• ren...
• Taken for less than 1 month
• February 22, 2022

For Dietary Supplementation "I took 200 mg and started to feel dizzy, heart and hands burning sensations, like a feeling of fear. I just want to relax. Never ever take it anymore."

• Joh...
• January 29, 2022

For Dietary Supplementation "Let’s be clear here: supplements like this have clearly helped some folks. I just happened to fall on the other side of things, and it needs to be shared. As with others, I had a good first few days, and then days 4 and 5 were something entirely different, with heightened anxiety and depression deeper than I have felt before (worsened existing depression). I only took 200 mg in the morning and 200 mg at night. The moral of the story is to start low and start slow and write down what is happening. Talk to someone before taking this, because it can sincerely mess you up. I am a slow metabolizer, and that may play a role in my experience, just not sure."

• Alm...
• Taken for less than 1 month
• December 14, 2021

For Dietary Supplementation "Started taking a nightly dose of two 200 mg L-Theanine 'Theanine Serene' doses (recommended serving size) to 'support relaxation & focused attention' during the day. Slept okay, but had VERY vivid, weird dreams each night to the point it made me distressed. Had a low-grade headache this morning, as well as slight stomach pain. Researched for negative side effects and bingo, here I am. This site is one of the few that posts user experiences without diminishing or glossing over negative side effects. After 4 days, I am throwing the rest away, bottle to recycling, and recommend anyone use this amino acid with prior research & caution. I am a 61-year-old female in good health, take minimal supplements & no prescriptions."

• gol...
• Taken for less than 1 month
• November 28, 2021

For Dietary Supplementation "I am a 21-year-old female with medicated ADHD, but no other health problems. Everything I've read has said that L-theanine helps with ADHD stimulant medication jitters, without any side effects. I took 200 mg yesterday afternoon. What followed was what I felt was the worst human experience imaginable. Within 40 minutes, and for 5 hours afterward, I was dissociating for the first time in my life (everything felt distant and like I wasn't in my own body), every muscle was twitching, I was easily startled, tachycardia, I could not stop crying, and every time I closed my eyes, all I could see were rapid flashes of light, as if I was seeing my own neurons firing off. This supplement took me to depths of sadness that I did not know were possible for anyone to feel. Even now, well over 24 hours later, whatever trace amount of L-theanine is still in my system has rendered my ADHD medication useless, and I am still unwell. I hope it clears within the next few days-I just want my life back."

• Eme...
• Taken for less than 1 month
• November 6, 2021

For Dietary Supplementation "Opened a capsule and took some, and immediately felt anxious, nauseated, and worried with palpitations. Will not try again."

• RJA...
• Taken for less than 1 month
• October 26, 2021

For Dietary Supplementation "I discovered L-theanine by accident through drinking green tea, which I noticed had a hugely positive effect on my mental state - feeling relaxed, calm, as well as alert with mental clarity. This led me to buy L-theanine supplements, and unfortunately, dosages from 40 mg to 400 mg each caused me physical and mental discomfort - headache, nausea, anxiety, and lack of focus. I wondered if I am sensitive to the L-theanine and should try out micro dosages."

• Iss...
• Taken for less than 1 month
• October 10, 2021

For Dietary Supplementation "I've had sleep issues for the past week since stopping smoking cannabis. I took nutritional advice at a health food shop and bought L-theanine and Serotonin 5-HTP. I took one each of the capsules shortly before going to bed last night, following the directions on the bottles. I had a terrible night with stomach pains and nausea, and then a headache developed. These symptoms have remained more or less constant, with a slight reduction for a time after taking paracetamol. It is now 4:25 pm. I will not be taking either of these supplements again."

• Lon...
• Taken for less than 1 month
• September 6, 2021

For Dietary Supplementation "I took one 200 mg pill of l-theanine to help me get rid of anxiety about one hour before I wanted to go to sleep. It elevated my anxiety with horrifying nightmares. In these nightmares, people looked like hideous mutants. I woke up several times, or I think that I did, and the horror was still playing. The nightmare came to life. That was an experience that I never want to relive! Ashwagandha works far better for me."

• Dis...
• Taken for less than 1 month
• August 11, 2021

For Dietary Supplementation "Bought l-theanine for sleep aid. Took it an hour ago, and now I'm suddenly having a lot of heart palpitations, which can't be just a coincidence."

• Tha...
• Taken for less than 1 month
• April 26, 2021

For Dietary Supplementation "I tried supplementing with L-Theanine for stress and noticed that I was getting random heart palpitations. When I stopped supplementing, they went away. It also hides in a lot of supplements. A friend's husband had the same issue from a natural sleep product that had L-Theanine in it."

• Anonymous
• Taken for less than 1 month
• March 8, 2021

For Dietary Supplementation "I took l-theanine combined with melatonin to help me fall asleep, and my experience was awful. It made me almost jittery, and although I was very tired, I couldn’t go to sleep because of the restlessness it caused. Once I did fall asleep, I woke up frequently feeling really anxious."

• lis...
• Taken for less than 1 month
• March 7, 2021

For Dietary Supplementation "I got horrible chest pain and tachycardia (fast heart beats) and palpitations from just 50 mg every time I took it. I haven’t found any warnings of these side effects for this until I came on here. This site is so helpful. Be very careful with this supplement. Start very low and look out for worsening mood and anxiety. I can’t believe no other websites list these common side effects."

• Pao...
• Taken for less than 1 month
• January 16, 2021

For Dietary Supplementation "Well, I tried l-theanine because I was taking ashwagandha, but I was still getting a little anxiety. The first day I started, I felt tingly and a little weak, but I thought maybe because it’s the first time, so I kept on taking it. By the third time, I started feeling a little sad for no reason, and then the fourth day I didn’t feel like that, but then the fifth day I felt negative again, and I wasn’t feeling like this with ashwagandha at all. So yeah, it’s not for everybody, so be careful."

• GBa...
• Taken for less than 1 month
• January 11, 2021

For Dietary Supplementation "Tried to take for general anxiety and for calmness. Just 100 mg, 3 days in a row, caused the opposite: insomnia, anxiety, and also a strange capability to bring up bad memories. Moved me more towards a depressive state of mind."

• Lil...
• Taken for 1 to 6 months
• December 30, 2020

For Dietary Supplementation "I've been using 200 mg of l-theanine combined with caffeine on and off for about 4 months now. At first, it was okay, but I would have this weird dizziness that would fade away after some time. I loved the way it kind of made me 'wake up' for hours so I could work and study with full focus. However, this month and last month have been horrible for me with regards to taking these pills. I've started to feel tingly and numb in the hands and feet, and I have this awful dizziness accompanied by horrible heartburn. I feel like I am living in another dimension right now as everything around me is spinning. I took the pills last night for me to finally realize that this isn't for me. I did not sleep all night long! I still feel restless 10 hours later, and the numbness, dizziness, and heartburn are still there. I am a perfectly healthy woman, and trust me, this supplement isn't for everyone, so be careful."

• pea...
• Taken for less than 1 month
• November 12, 2020

For Dietary Supplementation "I have had panic attacks for a few years now. I am on Effexor (75 mg) and Klonopin (very little). Since my doctor wants me off the Klonopin and my anxiety has seemed to get worse, I decided to find other alternatives. I looked to magnesium, which really seems to help. I noticed L-theanine, and like most of you, I took it and felt the anxiety. I was like, what? Isn't it supposed to relax me? Well, I felt just the opposite. It subsided on its own, and I wasn't sure it was the pill, so I took it again at bedtime, and yep, the same. So I won't be taking any more."

• Mil...
• November 11, 2020

For Dietary Supplementation "I took l-theanine at a 200 mg dose at 2 am in combination with 100 mg caffeine. I was hospitalized hours later. After the extreme weakness and dangerously low blood pressure it caused, panic attacks almost drove me crazy. It doesn't seem to work well for everyone."

• Nes...
• Taken for less than 1 month
• November 2, 2020

For Dietary Supplementation "I started taking l-theanine a month ago. At first, it caused me to have horrible nightmares. I've never had heartburn before, but now I do. I've been in a super weird mood too. Not feeling like myself. I've also noticed random heart palpitations."

• Ang...
• Taken for less than 1 month
• October 24, 2020

For Dietary Supplementation "I tried just one pill last night and shortly after felt really relaxed, like that feeling when you’re about to fall asleep. Then my heart was beating closer to 125 bpm for at least an hour or more. I felt dizzy and also nauseous. I won’t be taking this again."

• lif...
• Taken for less than 1 month
• September 24, 2020

For Dietary Supplementation "I write this as I was searching for adverse effects from l-theanine. Well, lo and behold, I see others on there have also experienced dizziness and strange symptoms. I currently take 1 mg of Klonopin and 50 mg of Zoloft daily. I decided to try 200 mg of l-theanine last night. My hands are still shaky as I type this almost 24 hours later. I was unable to leave my house today due to dizziness, exhaustion, depression, and anxiety. When I woke up last night to go to the bathroom, I felt like the room was spinning, and I awoke from a coma. I can only conclude that the l-theanine reduced my blood pressure to near zero. There were no indications that I could not take it with the medications I am on. Well, guess what? IT HAD A VERY BAD ONE! Those of you on medications, be very cautious!"

• Maz...
• September 2, 2020

For Dietary Supplementation "So I suffer from BPD and every type of anxiety, I guess. I found l-theanine and bought 450 mg ones. Took 2 pills before sleeping. Within 30 minutes, was knocked out without the daily suicidal thoughts. Everything was going so well. However, a month later, I was perfectly fine until I had a stomach ache. I went to the toilet a number of times and nothing was coming out. The following night, I had diarrhea. The worst ever experienced in my life! It was 2:30 a.m. and my stomach didn't let me sleep, so I went to the toilet. Story short, ended up unconscious in the hallway. Once I gained consciousness, I ran to the toilet again for the other half of rapid fire. It took all my energy. Today, after 2 months, again, was laughing with Mum until I had the worst stomach ache out of nowhere. I felt my body shutting down on me. I rushed to the toilet with the same signs and rapid fire before falling unconscious. Now I know it is l-theanine, I will not try these again. Please do not try this."

• Jjr...
• August 15, 2020

For Dietary Supplementation "My doctor suggested 100 mg 2x daily for general anxiety. I was reluctant in taking my other prescribed anxiety meds (i.e., Xanax), so I figured I’d give this natural alternative a try. I took the Integrative Therapeutics brand because I’d had good experiences with their lavender oil pills (which do work for me, by the way). I took my first pill of 100 mg about 15 minutes after breakfast. By the 45-minute mark, I was beginning to have the worst heart palpitations of my entire life. I thought I was going into convulsions. I tried to eat some bread to absorb the pill, but it began to feel as though my mouth wouldn’t function. I felt like I was losing control of my body. I was beyond irritated and incoherent. Mind you, I’ve suffered from anxiety attacks for the past five years, but nothing like this before. I’m also a 23-year-old, healthy woman. I’m not on any other medications. The extremely high heart rate lasted for close to two hours. This may work for some, but not for me."

• Anonymous
• Taken for less than 1 month
• July 17, 2020

For Dietary Supplementation "I only took two pills (200 mg each pill) over two days. The first day I seemed more focused, noticed I was reading through articles faster and seemed more alert, but not 'wired.' The second day, I felt really dizzy and brain foggy, anxiety spiked to where I felt like I couldn't even go outside, let alone go somewhere specifically, rapid heartbeat, and frequent trips to the bathroom. Threw the bottle in the trash and hopefully things will level back out in the next couple of days."