The beverage comprises carbonated water, lemon fruit from concentrate (2%), citric acid (acid), sodium citrate (acidity regulator), sweeteners (aspartame, sodium saccharin), ascorbic acid (antioxidant), potassium sorbate (preservative), natural flavourings including quinine, stabilisers (modified starch, glycerol esters of wood rosins), and colours (copper complexes of chlorophyllins, carotenes). These ingredients combine to deliver the signature taste of Schweppes Slimline Bitter Lemon, balancing sweetness with the characteristic bitterness of quinine. ​

Schweppes Slimline Bitter Lemon 24 × 200ml is free from the 14 major allergens, including gluten, dairy, nuts, soy, and sulphites, making it suitable for individuals with common food allergies. It is also gluten-free, GMO-free, and suitable for vegetarians and vegans. However, it contains aspartame, a source of phenylalanine, which may be unsuitable for individuals with phenylketonuria (PKU). Consumers are advised to check the product label for the most accurate and up-to-date information. ​

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