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Clarithromycin Concentration (Serum/Plasma)

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

This test measures the amount of clarithromycin, an antibiotic, in your blood. It helps determine if your medication levels are within the recommended range for effective treatment.

Quick summary

["Clarithromycin levels help ensure your antibiotic therapy is working properly."]

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

Key facts at a glance

LOINC
34638-7
Short code
Clarithro CSF-mCnc
Synonyms
Clarithro CSF-mCnc
Category
chemistry
Sample
csf
Container
Sterile tube
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
1-2 mL
Stability
Immediate analysis required, Refrigerated: 1h
Hemolysis max
200
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your healthcare provider may order this test if you’re taking clarithromycin to treat or prevent bacterial infections, such as pneumonia, ear infections, or certain types of skin infections. It may also be used to monitor long-term use or adjust dosing if needed.

What Does the Test Measure?

The test quantifies the concentration of clarithromycin in your blood plasma or serum. This helps assess whether your body is absorbing the antibiotic correctly and whether the dose is appropriate for your condition.

How Is the Sample Collected?

A blood sample is drawn from a vein, usually in your arm. The sample is then sent to a lab for analysis.

What Are Common Uses?

This test is primarily used to confirm therapeutic drug levels, detect drug interactions (e.g., with other medications), or identify potential side effects like liver issues in some patients.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clarithromycin is a macrolide antibiotic used to treat a variety of bacterial infections. Proper monitoring of its blood levels ensures effective treatment while minimizing risks of resistance or adverse effects. Abnormal levels may indicate poor absorption, drug interactions, or underlying health conditions affecting metabolism.

Short name

Clarithromycin Level

Frequently asked questions

What might cause my clarithromycin levels to be too low?
Low levels could result from improper dosing, poor absorption (e.g., due to stomach issues), or interactions with other medications that affect how clarithromycin is processed in your body. Your provider may adjust your dose or switch medications if needed.
What could happen if my levels are too high?
Very high levels may increase the risk of side effects, such as nausea, diarrhea, or, rarely, liver problems. Your healthcare provider will monitor you closely if you’re taking clarithromycin long-term or have conditions like kidney or liver disease.
Do I need to fast before this test?
No fasting is required for this test, but follow your provider’s instructions about when to take your clarithromycin medication. If you’re unsure, ask your lab or healthcare team for clarification.
  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