Some women experience distinct physical symptoms that clearly signal the onset of menstruation. These may be considered a special type of veset known as a veset haguf (physical veset).
Halachic sources that discuss veset haguf mention some more common premenstrual symptoms, like cramping—as well as unusual symptoms, like fits of sneezing or yawning.
A physical symptom can only be established as a veset haguf if a woman uniquely and consistently experiences it at a fixed time in conjunction with uterine blood-flow.
We follow the view that if such a symptom ends no earlier than one day before the onset of a woman’s blood-flow, then it is clearly considered a veset haguf. A woman with a clear, distinctive, and consistently-timed symptom that is more distant from her flow should ask an individual question to determine if she has a veset haguf.
If a woman has a certain symptom, sometimes in conjunction with her menstrual blood-flow and at other times unrelated to it, then the symptom is not considered a veset haguf.
So, for example, a woman who feels a distinct pain in her back within a day before the start of her period would treat it as a veset haguf, if she does not feel that type of pain at other times. However, a woman who frequently has cramping before her period, and sometimes has similar cramping at other times of the month, would not treat her cramping as a veset haguf.
Mood changes or a general intuition that one’s period is about to start are not considered a veset haguf. Bodily signs that require measurement to detect (like a temperature change), are usually not considered a veset haguf. Physical symptoms of ovulation (like secretions) are usually not sufficiently distinctive, or not sufficiently close to the onset of menstruation, to count as a veset haguf.