I developed an allergy to Dawn dish detergent that worsened very gradually. I couldn't figure out what was making my hands swell up every so often and at first thought it was a food allergy because it always happened after dinner. Then, one day, it dawned on me. Switched to a different product and all is well.
Interesting. My sister used to get warts on her hands whenever she smoked Merit menthol cigarettes. She used to switch brands now and then and that was how she noticed it. I knew of two other people that smoked Merit menthol and they had warts on their hands. When I mentioned my sister's noticing that when she changed brands the warts went away, these two guys changed brands and theirs went away too. The one even tried them again later, only to have his warts return. He stopped smoking Merit menthol after that.
Kins of strange how we all are different and certain things will affect us differently.