Medicines / Chemical Substances

All information on medicines / chemical substances

At a glance

There are various drugs and chemical substances that can have a significant influence on urine or sampling. Some only change thresholdvalues, others render the complete analysis unusable.
If the analyzer is unaware of the interfering substance, it can be relatively easy to make a false diagnosis, which can sometimes have serious consequences.

For more information

In the following table, schematically, some drugs or chemical substances that may have an influence on the urine sample are listed. The list is only an excerpt and has no claim to completeness.


Interfering substance 7 factor Influenced parameter
Amitriptyline Urine color (green)
Beta-carotene Urine color (yellow)
Betanin (Randen) Urine color (red)
Captopril Ketone (up), leukocytes (up), leukocytes (down)
Cefoxitin leukocytes (up), urobilinogen (down), protein (up)
Cephalexin Leukocytes (up)
Chemotherapy Nitrite (down)
Quinidine Protein (up)
Quinine Urine color (yellow-brown)
Chlorhexidine Protein (up)
Chloroquine Protein (up)
Clavulanic acid Leukocytes (up)
Curcumin leukocytes (up), ketone (up), protein (up)
Deferoxamine Urine color (red-brown)
Diurese / Diuretics Specific weight (down), nitrite (down)
Gentamycin sulfate Leukocytes (down)
Imipenem Leukocytes (up), ketone (up), bilirubin (up)
Indometacin Urine color (green)
Isoniazid Urine color (orange)
Preservation – Boric Acid Leukocytes (up)
Conservation – Formaldehyde Leukocytes (up), Urobilinogen (down), Ketone (up)
Preservation – Formalin Blood (down)
Long standing of the sample Nitrite (down) (up), Urobilinogen (down), Bilirubin (down)
Levodopa Urine color (red, black)
Meropenem Leukocytes (up)
Methylene blue Urine color (blue)
Metronidazole Urine color (black)
Mitoxantrone Urine color (green, blue)
Multivitamin preparations Urine color (green, yellow)
N-acetylcysteine Leukocytes (up), urobilinogen (down)
Sodium azide Leukocytes (up)
Nitrite Urobilinogen (down)
Nitrofurantoin urine colour (yellow-brown); leukocytes (up), protein (up), glucose (down)
p-aminosalicylic acid Protein (up), Urobilinogen (up), Bilirubin (up)
Penicillin Bilirubin (up)
Phenazopyridine Nitrite urine color (orange red) (up), urobilinogen (up), bilirubin (up), blood (up)
Phenolphtalein Urine color (yellow-brown)
Phenylketone Keton (up)
Phenytoin Urine color (brown-red)
Phthalein compounds Ketone (up)
Polyvinylpyrrolidone Protein (up)
Mercury salts Leukocytes (up)
Cleaning agents (oxidizing) Blood (up)
Rifampicin Urine color (red)
Hydrochloric acid Leukocytes (up), Bilirubin (up)
Sulfamethoxazole Urine color (brown-red), urobilinogen (up)
Sulfonamide (trimethoprim) Nitrite (down)
Tetracycline Leukocytes (up)
Thiol Groups Ketone (up), nitrite (down), glucose (up), bilirubin (down), blood (down)
Triamteren Urine color (blue)


  • Roche Diagnostics Deutschland GmbH (2014): Compendium of Urinalysis. Urine Test Strips and Microscopy, 1-196
  • Roche Diagnostics Deutschland GmbH (2009): Nierendiagnostik Grundlagen der Labormedizin, 1-60
  • Strotmann, F. (2017): Was der Urin verrät , URL: , Retrieved 18.06.2019
  • Hecker, M.T. & Donskey, C.J. (2014): Is antibiotic treatment indicated in a patient with a positive urine culture but no symptoms? Cleveland Clinic Journal of Medicine, 721-724
  • S3-Leitlinie (2017): Epidemiologie, Diagnostik, Therapie und Management unkomplizierter bakterieller ambulant erworbener Harnwegsinfektionen bei erwachsenen Patienten. (AWMF register number: 043-044),
Status of information: 2022