While low oxygen saturation levels and breathing difficulty require hospitalisation, there are several other symptoms that are equally critical. A lesser-known one appears on your skin, lips and nails. Pale, grey, or blue-coloured skin, lips, or nail beds also require immediate medical attention. The change in colour depends on skin tone, but it should not be taken lightly. The change or discolouration is easily visible in people with a darker skin tone, especially around lips, eyes, or mouth.