A drop of lemon or lime juice on acne scar is said to lighten the blemish, but the psoralens present in lemons can cause a phototoxic reaction on the skin when it’s exposed to UV light. That means your attempt to fade a red spot could result in a big blister.
Eggs are a popular ingredient in K-beauty products, but applying them directly to the skin can have some pretty ugly consequences. Raw eggs can give you a bacterial infection.
Cinnamon has some antimicrobial benefits but its hypersensitivity can lead to unwanted side effects like skin irritation, discoloration, and burning.
The practice of using toothpaste to treat acne is widely popular but it can irritate and inflame the skin.
Vinegar is highly acidic and can cause skin irritations and burns. So, one should avoid using vinegar directly on the skin.