L-theanine and Increased Heart Rate: What Users Say

• 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."

• 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."

• Jil...
• Taken for less than 1 month
• December 15, 2019

For Dietary Supplementation "Last night before I crawled into bed, I took two L-Theanine. Within 15 minutes, I felt a massive wave of relaxation and fatigue sweep over me. I honored my feelings despite it being relatively early in the evening and turned out the lights at 8:30. Within an hour of falling asleep, I experienced a horrifying dream. I rarely dream, so this was something rather unusual for me. Following my dream, I awoke an hour or so later with my heart pounding. Thank goodness I was able to successfully fall back to sleep. I have yet to try this supplement during the day, which I've read can help manage feelings of stress and anxiety in the workplace and at home. I was really impressed with how quickly this product promoted a sense of peaceful relaxation. I think L-Theanine may become a product I can depend on that will help calm my mind and settle my emotions as I prepare for a sound, restful night's sleep."

• Baz...
• Taken for less than 1 month
• August 17, 2020

For Dietary Supplementation "I read this supplement could help with withdrawals from fluoxetine, so I took a 400 mg dose (the only dosage I could find) with magnesium before going to bed. I slept very poorly that night (could have been unrelated, though). But the next day in the morning, I experienced a feeling of panic and rapid heartbeat that completely freaked me out. I was driving and thought I was going to black out. I don't get panic attacks or severe anxiety, so I decided to stop this supplement immediately. I would recommend starting on a very low dose if you are going to try this."

• jiv...
• Taken for 2 to 5 years
• April 27, 2021

For Dietary Supplementation "I've been using this for years. The first to counter glutamate sensitivity or reactions, which it does very well. I've used it to relax, but (for me) it lasted too long. I felt my most relaxed and tired about 8 hours after I took it, so I assume it has a long half-life. It's not something to chill you for 2 or 3 hours. For the last 9 months or so, I've been using it to help sleep. Just 100 mg a few hours before bed helps, but doesn't keep me asleep for more than 4 hours. I find adding anything to this, like melatonin or inositol, to improve sleep just causes side effects. In fact, just the L-theanine alone after 8 months or so of use started to cause all-day dizziness and headaches that made me have to stop using it. I keep it now in case I eat something dining out that's very high in glutamate (like seafood) or has unlabeled MSG, as I do get reactions like elevated BP and pulse, which this definitely helps with. Great for occasional use."

• Kmj...
• Taken for 1 to 6 months
• March 11, 2022

For Dietary Supplementation "So far, pretty good after a month. Taking 200 mg twice a day for stress and anxiety, with heart racing, shaking, sleeplessness. Certainly takes the edge off, but honestly, not working as well as I thought it would. I have high hopes, as I became seriously addicted to tranquilizers and antidepressants 10 years ago, and it took me a year of horror to get off them. My body simply doesn’t metabolize these drugs. So no way will I ever take another, and so hoping l-theanine will help through my anxiety, as the older I get, the more anxious I seem to become as life happens while we plan it. Thanks, everyone, for sharing your experiences."

• Rut...
• Taken for less than 1 month
• April 15, 2020

For Dietary Supplementation "This drug increased heart rate, felt sedative, and at the same time, more depressed and stressed."