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Fluoroquinolone Antibiotic Level (Serum or Plasma)

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

This test measures the amount of fluoroquinolone antibiotics (such as ciprofloxacin or levofloxacin) in your blood or plasma. It helps doctors determine if your medication levels are within an effective range.

Quick summary

["Check your antibiotic levels to ensure they’re working properly."]

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

Key facts at a glance

LOINC
41135-5
Short code
FLUAV N8 Ab Ser Ql
Synonyms
FLUAV N8 Ab Ser Ql
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

Doctors may order this test if you’re taking fluoroquinolone antibiotics for a long-term infection, such as a urinary tract infection, respiratory infection, or certain types of bacterial infections. It helps ensure the medication is at the right concentration to fight the infection without causing side effects.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into your arm or vein to draw blood. If you’re taking this test for urine or other fluids, follow your doctor’s instructions for sample collection.

What the Results Mean

Results show the antibiotic concentration in your blood or fluid. Low levels may mean the infection isn’t being fully treated, while very high levels could indicate side effects or improper dosing. Your doctor will interpret these results in the context of your medical condition.

Common Uses and Considerations

This test is particularly useful for monitoring patients with kidney or liver issues, as these organs help clear antibiotics from the body. It may also be used in cases where the infection is resistant to standard doses.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Fluoroquinolone Drug Level

Frequently asked questions

How often should I get this test?
Your doctor will determine the timing based on your treatment plan, the type of fluoroquinolone, and your medical condition. Typically, it may be done at specific intervals (e.g., 24–48 hours after dosing) to check levels.
What if my results are too high or too low?
If levels are too high, your doctor may adjust your dose or switch medications to avoid side effects like nausea, tendon pain, or allergic reactions. If levels are too low, they may increase your dose or switch to a different antibiotic.
Can I drink or eat before this test?
For blood tests, you can eat and drink normally unless instructed otherwise. For urine tests, follow your doctor’s instructions, as some may require fasting or specific timing.
  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