A rubella or German measles rash tends to consist of small, flat pink spots. But these can also run together to form red blotches, making it difficult to differentiate between the rash of measles and the rash of German measles.
If the rash is confined to the face, then it may be acne. If it is accompanied by severe pain, then shingles is a leading contender. On the feet, athlete's foot is a possible diagnosis, and likely to be a condition known as intertrigo.
When a rash consists of weeping, pus-filled spots, then impetigo is the most likely diagnosis.
Among babies and small children, ordinary heat rash is the most common. Although it usually occurs - as its name suggests - in warm weather, a heat rash can also develop in the cold if the baby is covered with too many clothes or bed clothes.
Many articles taken from 'A word with the doctor', by Dr. John Windsor.