L-theanine side effects: what to check on the label

Label check

Side effect checklist

• Active ingredients: confirm L-Theanine and the amount per serving rather than relying on the front label.
• Serving context: compare Capsule and 1 capsule with how often the label says to use it.
• Allergens and inactive ingredients: check flavors, sweeteners, capsules, gelatin, oils, dairy, soy, gluten, fish, or shellfish when they matter to you.
• Overlap: count similar ingredients from multivitamins, powders, blends, gummies, drinks, and topical products before adding another product.
• Check dose, form, allergens, medication cautions, health conditions, pregnancy or breastfeeding context, and total intake from overlapping supplements.
• Use the current product label first because formulas, serving sizes, and warnings can change.

Before using

Label issues to check

Safety signals

When to stop and get help

• Get urgent help for trouble breathing, facial or throat swelling, severe hives, fainting, chest pain, or a severe allergic reaction.
• Stop using the product and contact a clinician if you notice a severe rash, persistent vomiting, severe diarrhea, black or bloody stool, yellowing skin, or unusual weakness.
• For topical products, stop and seek help if scalp or skin irritation becomes severe, spreads, blisters, or involves the eyes.
• For children, pregnancy, breastfeeding, major medical conditions, or multiple medications, use clinician guidance before relying on a supplement label alone.

This page is educational and does not replace care from a qualified clinician.

Product context

Why side effects can differ

Theanine 200 is a Relaxation product from Jarrow Formulas. Side effects can depend on dose, form, inactive ingredients, allergies, medication use, health conditions, and whether you use similar products at the same time.

Price context: $0.31 per serving estimate at last check; retailer prices can change.

Ingredients and goals

Follow the ingredient, then the goal

Connected ingredients: L-Theanine. Connected goals: Stress, Sleep.

Safety notes

Cautions recorded for review

These notes may include ingredient-level guidance, not verified adverse reactions to this exact finished product. Product-specific reaction frequencies have not been established by this record.

• Review label cautions and ingredient context before use.
• Medication: Check sedating medications, alcohol use, or other calming supplements before combining.
• Possible side effect: Drowsiness, headache, or lower alertness may occur for some users.
• Pregnancy/Breastfeeding: Pregnancy and breastfeeding safety data may be limited; ask a healthcare professional.
• Ingredient context: Screen pregnancy, breastfeeding, sedatives, blood pressure medication, and daytime sleepiness context.

Serving and label record

Recorded serving: 1 capsule

Recorded active amount: Not recorded

Product form: Capsule

These are database entries, not a personalized dose recommendation. A serving size alone does not establish daily frequency, age suitability, duration, or route of use. Follow the directions on your exact package; formulations and country-specific labels can differ.

Record verification date: 2026-07-23

This date describes the product record; it does not confirm that every warning or allergen field has been reviewed.

Product label source: not recorded.

Allergens and inactive ingredients

Allergen information has not been verified in this record. No listed warning does not mean allergen-free.

Complete ingredient list, contains/may-contain statements, and manufacturing cross-contact information: not confirmed by this summary. Check the current package or manufacturer. Do not treat a dietary preference filter as an allergen guarantee.

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