Does it happen en masse or does each woman have their own heat season? Say, does everyone go crazy during the same 2-3 weeks or does it vary per person like it happens with periods?
In the masse heat I think there would be some obvious differences in stuff like festivities and each culture would adapt to these seasons. There would be a need to gather and store resources before the rut, and also to be prepared for the inevitable birthing en masse to come. We would probably have public holidays for the mating seasons and festivities for birthing season. In contemporary times, hospitals would need to do some heavy work planning and preparing maternity ward space to accommodate the seasonal influx. That’s just what pops to mind.
Not too sure about the differences in the second case though. One option is, women would be allowed to retreat from society and become hermits during heat if they want to avoid pregnancy and this would be totally normal. Or, some cultures would lock them to prevent them getting pregnant. Coming to think of it, I think having women randomly in some kind of irresistible heat like this would be very disruptive and impossible to prepare for so I don’t see much happening in the way of gender equality and women’s rights sadly. I’m inclined to think the re would be a lot of gender based extreme segregation.
The allergy part may sound outlandish but it happened to me with headphones. They were made of some kind of rubbery plastic which was absolutely fine for the first 2 years I used them, and then they became impossible to wear. Cleaning the headphones did nothing and the allergy got pretty gross, I had to see a doctor. Fortunately an ointment fixed my ears but I had to get new headphones. My guess is that the material they were made of started to degrade/change chemically with time, like faux leather and rubber does, and my skin developed an allergy to it.