Due to the presence of pigmented substances such as urochrome, urochrome and urobilinogen, normal human urine is a pale yellow transparent liquid.
In addition, the color of urine is influenced by various factors such as diet, medication, exercise and disease. The presence of abnormal urine color, especially red color with urinary tract irritation, is often an alarm signal of disease.
However, it is important not to assume that red urine is the result of disease at first sight, as it may be the result of certain medications. Some of the drugs that may cause red urine are summarized to alert medication users.
Rifamycins
This class of drugs includes rifampicin, rifaximin and rifapentine. The metabolites have pigmented groups and are excreted in a wide range of ways, so they can cause a variety of secretions such as tears, saliva, nasal secretions, sweat and urine to be red in varying degrees.
Nitroimidazoles
This class of drugs includes metronidazole, tinidazole and ornidazole, the metabolites of which can make the urine dark red.
Anthracycline antineoplastics
This class of drugs includes adriamycin, epirubicin, erythromycin and idarubicin, which can cause red staining of urine within 1~2 days after administration and usually disappears after 2 days.
Pigmented substances
Some plant or mineral-based herbal medicines contain natural pigments, which are not absorbed by the body when ingested in high amounts and are excreted from the urine, such as safflower and ochre. Others such as senna, rhubarb and vitamin B2 (riboflavin) can also make the urine dark yellow or even brown.
Warfarin
The urine may be red to orange during the administration of the drug for those with alkaline urine; the color may disappear when acidifying the urine to a pH less than 4.
Hydroxocobalamin
It is a deep red compound, which is a precursor substance of vitamin B12. It is made by replacing the cyanide group of vitamin B12 with hydroxyl group, and it can combine with cyanide ion to form cyanocobalamin in the body and act as detoxification, and is used clinically for cyanide detoxification. Hydroxocobalamin can cause red staining of skin, urine and other body fluids.
Imipenem Cilastatin
Changes in urine color can be seen, especially in children with the drug can appear non-bloody red urine, which is caused by drug coloring and should not be confused with hematuria.
Levodopa
80% of the drug is degraded into dopamine metabolites within 24 hours after oral administration, mainly homovanillic acid and dihydroxyphenylacetic acid, which are excreted by the kidneys. The metabolites can cause red urine and may also turn black or brown.
Salicyclovir
May cause orange-red urine.
Fenaminophen
This drug may cause the urine to turn pink, red or reddish-brown.
Desferrioxamine
Used to treat chronic iron overload, iron complexes can make urine brownish red.
Clofazimine
Used for the treatment of oncotic leprosy. It can make urine, sweat, breast milk, semen and saliva light red.
Clofazimine
Used in the treatment of malaria. Urine may be red after administration.
Mesalazine
It is used for the treatment of ulcerative colitis. It is metabolized to N-acetyl-5-aminosalicylic acid and excreted in urine as colorless, but may appear reddish brown when combined with detergents containing hypochlorite.
Methyldopa
It is used for the treatment of hypertension and is excreted mainly in its original form via the kidney. It can also be combined with hypochlorite-containing detergents and appears brownish or even reddish-brown.
Epalrestat
This product is used for the treatment of diabetic neuropathy and may appear maroon in the urine after administration.
The red color of urine caused by the use of the above drugs is a normal reaction caused by the drugs and needs to be distinguished from hematuria.
In addition, clinical attention should still be paid to hematuria caused by urotoxic drugs, such as non-steroidal drugs, aminoglycosides, vancomycin, cyclophosphamide, etc., which are more toxic to the urinary tract and may also clinically manifest as red hematuria when used, and once similar symptoms occur, prompt medical attention should be sought.