Onions And Antibiotics - A Bad Combination

Leticia Celentano Author: Leticia Celentano Time for reading: ~2 minutes Last Updated: January 27, 2026
Onions And Antibiotics - A Bad Combination

Half a head of onion a day against inflammatory processes, nutritionists recommend.

The unique combination of flavonoids and sulfur compounds make onions a food useful for daily consumption.
 
According to the Indicative Daily Intake ( RDA ), 150 g of onions contain: vitamin C - 19.7% of RDA; fiber - 10.8%; molybdenum - 10.6%; manganese - 10.5%; tryptophan - 6.6%; potassium - 6.2%; vitamin B 6 - 9.5% and only 64 calories or 3% of ODP.
 
Although a limited number of studies have been conducted on the nutritional value of onions, all available data reveal its anti-inflammatory properties. They are mainly due to Onionin A - a unique sulfur molecule for the plant. It suppresses the action of macrophages - specialized white blood cells that play a major role in the human immune response . Their role is important for the protection of the body, but their suppression in conditions of unwanted chronic inflammation may be an effect when consumed.
 
Another antioxidant in onions, quercetin , also has enviable anti-inflammatory properties, but it works differently. It mainly protects against the oxidation of fatty acids. When the body has low levels of oxidized fatty acids, it sends far fewer pro-inflammatory signaling molecules, thus achieving a more controlled immune response.
 
It is important to note that when cooking onions, quercetin does not break down from the temperature. It is only transferred from the onion to the broth, which is obtained by cooking.
 
Although not as potent as garlic allyl sulfide, quercetin is a potent antibacterial agent. Several studies have shown that it suppresses Streptococcus mutans and Streptococcus sobrinus , bacteria involved in the formation of caries. It is also strong against Porphyromonas gingivalis and Prevotella intermedia - bacteria that cause gingivitis . 
 
Its daily intake is recommended for asthmatics , because quercetin has recently been discovered a strong blanch -dilator - a compound that dilates the bronchi and facilitates the flow of air to the lungs. It also inhibits the release of histamine and other body compounds that cause allergic reactions.
 
 
Quercetin also controls serum immunoglobulin E levels , which are elevated in eczema sufferers; reduces the release of histamines and relieves the symptoms of pollinosis; slows the excretion of unabsorbed vitamin B3.
 
However, its consumption should be consistent with the use of antibiotics, because in combination with some of them, some side effects of drugs can be triggered. The most dangerous combination is with an antibiotic based on fluoroquinolones such as Quinolone , in which the additional intake of sulfur compounds and quercetin from onions can lead to swelling of the liver , accompanied by pain and possible damage to its hepatocytes.
 

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