Pickles (cucumbers or other vegetables preserved in brine or vinegar) accumulate biogenic amines including histamine when naturally fermented.

The key distinction is how they were pickled: naturally fermented pickles (made with salt and water, left to ferment with lactic acid bacteria) develop more histamine than vinegar-pickled products (most supermarket pickles, simply preserved in vinegar without true fermentation). Quick refrigerator pickles (cucumbers soaked briefly in seasoned vinegar) have the lowest biogenic amine content because there is minimal fermentation time. For people with histamine sensitivity, checking the label for the word 'fermented' or a long ingredient list involving salt-brine is a useful guide to histamine level.