Amino acids play an important role in key functions such as neurotransmission, transportation of fats, making of proteins, etc. In the form of proteins, these acids constitute a sizeable portion of your body. Amino acids also have a critical role to play in metabolism as well as bio-synthesis. L-theanine is a type of amino acid abundantly present in black and green teas. It is also known to be present in a few types of mushrooms. Its antioxidants are known to calm and relax your body. Many believe l-theanine to possess properties that can treat sleeplessness (insomnia or other sleep related disorders). But, l-theanine can also trigger a few side effects; staying aware of its side effects can give way to safer consumption of this drug.

L-theanine is mainly used for calming and relaxing your mind. Medical research done on people with a few mental conditions (such as schizophrenia) found reduced levels of anxieties in those who used this drug. If administered along with caffeine, this substance is known to boost attentiveness as well as mental agility. Nearly 40 milligrams (mg) of caffeine along with about 100 mg of l-theanine is known to have increased focusing skills and concentration levels.

Here, you are advised to remember that a standard serving of coffee has caffeine to the tune of ~ 90 mg. We live in times of pandemics such as covid-19; it is noteworthy that l-theanine can reduce the likely risks of infections – especially in the top parts of your respiratory tract. Green tea – known for a specific category of antioxidants known as catechins – is found to control common cold and to keep flu at bay.

L-theanine is also used for the management of high blood pressure – i.e., hypertension. Though coffee (especially, caffeine) also possesses capabilities to lower your blood pressure, the benefits are not as wide and profound as l-theanine. You also need to note that this substance is also linked to increasing your immunity levels, to fight risks of cancers, other such autoimmune medical conditions. Several studies – done at closely controlled lab environment – have evidenced an association between the intake of l-theanine and a reduced incidence of cancers in pancreas, ovaries, etc.

Side effects of l-theanine

Adverse side effects associated with the intake of l-theanine are very rare. It is considered safe to take most types of teas. It is also considered relatively safe to take supplements of l-theanine. However, the manufacturing of supplements of this substance does not come under the purview of the food and drug administration (FDA) in the US. Hence, it is highly recommended to exercise needful caution while buying this product. It is recommended to read the contents of the label or items printed on the product’s packaging.

A few clinical studies have identified some adverse side effects. For instance, tea with rich amounts of amino acids is known to interfere with anti-cancer medications. If you are already taking medications to treat cancers, co-administration of such types of teas (rich in amino acids) is known to trigger undesired reactions and side effects; one such key side effect is a likely reduction in the therapeutic properties of chemotherapy drugs. It is an essential aspect which calls for proactive consideration, prior to starting your medication plan. Teas with amino acids (such as green teas) can trigger irritation, stomach problems such as nausea or indigestion, etc.

In order to avoid spells of nausea, your pharmacist or treating physician will advise not to take l-theanine along with intoxicating substances such as alcohol. In general, nausea is observed among those who took l-theanine with other foods or drugs. In some remote instances, people complained of nausea when they took this drug along with caffeine. It is strongly recommended to take this supplement in smaller dosage forms. If nausea persists, check your diet or current medication plans to isolate the possible causes. You may also check with your physician or pharmacist to manage persistent spells of nausea. Your medical team may tell you not to consume l-theanine over an empty-stomach; instead, take the drug at a time that corresponds with your meal times – preferably post-meal.

A few other side effects of l-theanine

Some people who took l-theanine have experienced dizziness as well as abdominal discomforts. Abdominal problems or gastrointestinal disorders are quite rare though. People who took l-theanine in smaller doses never had such discomforts. Also, people who took these supplements prior to a meal reported a few problems in their gastrointestinal system; in order to avoid such problems, you are advised to consume l-theanine at least 90 minutes after a meal. People who took the drug after a meal rarely reported any of the aforesaid discomforts.

Other side effects include loss of appetite (though scientific conclusions are not present to substantiate this side effect, a few anecdotal evidences are however available), a marked reduction in blood pressure level, etc. Hypotension is often construed as a benefit among people who live with higher levels of blood pressure. But, this capability ceases to be a benefit for people with no blood pressure related problems.

At times, l-theanine can lead to conditions wherein you may find it difficult to maintain your concentration level or remain focused. This is a paradoxical reaction, because this supplement is taken (along with caffeine) to enhance your ability to focus. The good news however is – such a loss of focus develops only when l-theanine is taken in excessive levels. Clinical studies attribute the rate of metabolism as well as your genetic make-up as possible reasons for reduction in concentration levels. It is one of the reasons why dietitians advice intake of l-theanine with caffeine.

Allergies and hypersensitivity

You may need to be watchful of respiratory problems (such as gasping for breath or wheezing) and also a feeling of tightness in chest. You need to inform your treating doctor and pharmacist about already known allergies or hypersensitivity to green teas or l-theanine. People with allergies have reported discomforts such as itchiness, inflammation of facial or oral parts, fever, coughing spells, etc. If the allergy turns into an acute condition, it can lead to discoloration of skin, epileptic fits or spasms, seizures, convulsions, etc. Upon experiencing any of these signs, it is strongly recommended to take medical help as promptly as possible. A few other adverse symptoms you may need to stay aware are a decrease in blood pressure levels or pulse rate. Hypotension can be identified by its distinctive signs and symptoms – such as, excessive levels of weariness, dizziness, feeling thirsty most of the time, paleness of skin, fainting or passing out. In remote instances, people have reported loose stool, spells of headaches, vomiting, etc.

Headaches are also reported when higher dosages of l-theanine are taken. As a countermeasure, you are advised to take lower amounts of this supplement to avoid chronic spells of headache. As another precautionary measure, you can also take it along with caffeine; this combination is considered safe and it is not known to trigger headaches. Such a combination is also useful if you are advised to take larger doses of l-theanine. If your headaches persist for long – even after taking it along with caffeine – you are advised to talk to you treating doctor or pharmacist as quickly as possible.

Those who are already taking drugs to treat anxiety need to seek advice from their treating doctor on how safe it is to take l-theanine. As this supplement can boost sleepiness, you are advised not to drive or in general, engage in activities that may need a high level of mental alertness or agility. It is also not advised to operate heavy machines, for instance. As an added precaution, it is not a good practice to take supplements of l-theanine along with alcoholic drinks such as wine, beer, etc.

Women who are pregnant need to stay away from this drug. Also, women who are planning to get pregnant are advised not to take l-theanine. Those who have pregnancy plans need to take contraceptives while using this drug. Supplements of l-theanine are known to pass through breastmilk; hence, it is not a good practice to take them while you are nursing a baby. For more inputs on these aspects, you are advised to talk to your treating doctor or pharmacist.

Medical studies have not clearly ascertained the risks of taking supplements of l-theanine for a longer span of time. Dosage of l-theanine is a key aspect that can determine how safe it is to take this supplement. A safer dose is in the range of 100 to 150 milligrams, taken once each day. However, some people may consume excessive amounts of l-theanine, without knowing its adverse side effects. As these supplements are not governed by federal agencies (like the food and drug administration), it is important to check for the availability of certificates of analysis, issued by authentic or reliable third parties. It is equally essential to check if the manufacturer has used a pure form of this substance or a derivative of D-theanine along with other such impure items, mostly used as an excipient and as a filler.

An overdose of l-theanine and possible side effects

In remote cases, people who took heavy doses (i.e., overdoses) of l-theanine have reported being extremely relaxed or slip into a sedated condition. In such instances, you are likely to experience loss of focus, concentration, slow down of breathing, an acute spell of dizziness, episodes of weakness, feeling drowsy or passing out. If you experience any of these signs, you need to take medical attention at the earliest possible time. If you are living in the US, you are advised to call 911 immediately or get in touch with a poison control center closer to your home. On the other hand, those living in Canada are advised to call Health Canada, or reach out to the poison control center located in your province without any delay.

You also need to remember that the abovementioned side effects do not constitute a full list of possible reactions, discomforts or allergies. If you are noticing newer signs or symptoms, you need to talk to your treating physician and explain the discomforts. It is important to reach out to the emergency helpline numbers of the food and drug administration in the US.

In sum, very acute side effects triggered by consuming l-theanine are not common. But, as manufacturing of these supplements does not fall under the purview of food and drug administration, needful caution is required. Some of the side effects of this drug include stomach problems such as nausea or indigestion, etc. In general, it is highly recommended to consume these supplements in lesser dosages. Other adverse side effects include a loss of appetite, reduction in blood pressure level, etc. Always remember that people who took l-theanine in lesser dose forms rarely experienced many of these discomforts. Also, those who consumed l-theanine after a meal reported much lesser discomforts than those who took it before a meal. If abdominal problems are persisting for a longer time, you are advised to talk to your treating physician and pharmacist immediately.

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