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Lamotrigine concentration in serum/plasma

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

This test measures the amount of lamotrigine, a medication used to treat certain seizures and mood disorders, in your blood.

Quick summary

["Knowing your lamotrigine levels helps doctors monitor your dose and ensure it’s working safely for your condition."]

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

Key facts at a glance

LOINC
25458-1
Short code
lamoTRIgine SerPl-sCnc
Synonyms
lamoTRIgine SerPl-sCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why This Test Is Done

Your doctor may order this test if you’re taking lamotrigine to check if your dose is appropriate. It helps prevent side effects like rash or seizures while ensuring the medication is effective. This is often done during the first few months of starting the drug or when your dose changes.

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. If you’re on blood thinners, let your doctor know before the test.

What the Results Mean

Results are compared to a range that’s typical for healthy individuals on lamotrigine. Too high or too low levels can affect how well the drug works or increase side effects. Your doctor will discuss your specific results with you.

Possible Side Effects and Risks

While rare, very high levels of lamotrigine can cause serious health risks, such as seizures or kidney problems. Mild side effects from the blood draw include bruising or soreness at the injection site.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Lamotrigine Level

Frequently asked questions

What does a high or low lamotrigine level indicate?
High levels may suggest your body is metabolizing the drug too quickly, which could reduce its effectiveness. Low levels might mean the dose isn’t enough to control your condition safely. Your doctor will adjust your medication based on these results.
How often should I get this test?
Your doctor will determine the timing based on your treatment plan. Typically, it’s done during the first few months of starting lamotrigine or when your dose is changed, but this can vary.
Can I eat or drink before this test?
You can eat and drink normally before the test unless your doctor advises otherwise. No fasting is required for this blood test.
  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