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Lamotrigine Substance Concentration (Serum or Plasma)

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of lamotrigine, a medication used to control seizures, in your blood. It helps your healthcare provider monitor your dose and ensure it’s working safely.

Quick summary

["This test helps adjust your seizure medication to avoid side effects or reduce seizures effectively."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
59919-1
Short code
lamoTRIgine Ur-sCnc
Synonyms
lamoTRIgine Ur-sCnc
Category
chemistry
Sample
urine
Container
Sterile urine container
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
10 mL
Stability
Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your doctor may order this test if you’re on lamotrigine to check if your dose is appropriate. It’s especially important right after starting the medication or when changing your dose to prevent side effects like rash or dizziness.

What to Expect Before the Test

No special preparation is needed. You’ll have a small needle inserted into your arm or vein to draw blood. It usually takes a few minutes, and you may feel a brief pinch. If drawn from a vein, you might have a small bruise afterward.

What the Results Mean

Results show your current lamotrigine level in your blood. Your doctor will compare this to your usual range to guide dosing. Too little may mean seizures aren’t controlled, while too much could increase side effects.

Common Side Effects to Watch For

While rare, high levels may cause dizziness, rash, or nausea. If you experience severe side effects like trouble breathing or swelling, seek medical help immediately.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Lamotrigine Level

Frequently asked questions

Why do I need this test if I’m already on lamotrigine?
Your doctor may order this test periodically to ensure your dose is safe and effective. It’s particularly important if you’ve recently changed your medication, had a seizure, or are experiencing side effects.
How often will I need this test?
Frequency depends on your treatment plan. Some people need it monthly, while others may only need it when their dose changes or if symptoms arise.
What if my results are outside the usual range?
If your results are unusually high or low, your doctor will review your dose and other medications. They may adjust your lamotrigine dose or check for interactions with other drugs you’re taking.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy