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Hypericum perforatum (St. John’s Wort) Immunoassay, Qualitative

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

This test checks whether your body has detected exposure to St. John’s Wort, a plant used traditionally for depression and anxiety. It does not measure active drug levels but confirms if the plant’s components have entered your system.

Quick summary

["This test helps monitor potential interactions with medications or assess exposure to herbal supplements."]

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

Key facts at a glance

LOINC
98232-2
Short code
St. John's wort IgE Qn
Synonyms
St. John's wort IgE Qn
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

What This Test Measures

The test detects specific antibodies or other markers in your blood that indicate your immune system has recognized St. John’s Wort components. This is done through an immunoassay method, which identifies the presence of these markers qualitatively (yes/no).

Why It Might Be Ordered

Your healthcare provider may order this test if you’ve taken St. John’s Wort supplements or are considering them, especially if you’re on prescription medications that could interact with it. It helps ensure safety by confirming exposure before or after use.

How the Test Works

A small blood sample is taken and analyzed to detect the presence of antibodies or other markers linked to St. John’s Wort. The result is qualitative, meaning it only tells you if exposure occurred, not the amount.

What to Expect Before the Test

No special preparation is needed. You may eat and drink normally on the day of the test. If you’re on blood-thinning medications, let your provider know before the draw.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

St. John’s Wort Exposure Test

Frequently asked questions

Will this test show if I have St. John’s Wort in my system even if I haven’t taken it recently?
No, this test only detects markers of past exposure. It won’t show current levels of St. John’s Wort in your system unless you’ve recently taken it.
Can this test be used to measure how much St. John’s Wort I’ve consumed?
No, this qualitative test confirms exposure but does not provide a quantitative measure of the amount consumed or active drug levels.
What if my test result is positive but I haven’t taken St. John’s Wort?
A positive result could indicate exposure through environmental sources (e.g., food, supplements, or herbal products) or cross-reactivity with other substances. Always discuss your results with your healthcare provider for further evaluation.
  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