Allergic Reactions vs. Irritation

Allergic reactions are the immune response to an allergen. The body notices the pesky substance and does all it can to get rid of it, alerting all senses and the body's own army to attack the unwelcomed guest and protect you at all costs.
When this happens often and for different or unrelated allergens, we can state that the person has a sensitive immune system and due diligence to investigate what they eat, drink and apply to their skin is a must.
Some allergic reactions (depending on the hyped nature of the immune response) can be very mild to severe in which your total health is now at risk and medical attention is required. Most commonly, the reaction will occur within moments of exposure to the allergen whereas for some, it can be a gradual build up with prolonged exposure.
Irritation is a tricky one, because often we dismiss a small symptom such as a little itch or just abit of redness as being 'nothing' when in fact it is a sign of an allergic reaction and we should cease using, eating or drinking whatever it was that caused it. If we ignore the small signs then we can potentially be stressing the body out more and then further fight from the immune system is required.
Anaphylaxis is the most severe form of allergic reaction and caution must be taken to avoid any and ALL product related to the known trigger.
Sometimes we will discover in adult life that we are in fact allergic to something we never had an issue with before. This is because, as we get older our immune response changes to a less fierce status placing us at higher risk for developing allergic reaction, irritations and unfortunately experiencing infections both internally and externally as a result.
So it is best that when you try something new, you patch test or take in only a small quantity as a safeguard. Much like dipping your foot into the water to see if its the right temp before plunging in.
Link: Aging Immunity
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5291468/#:~:text=Beginning%20with%20the%20sixth%20decade,to%20support%20appropriate%20wound%20healing.
Link: Allergies and Hypersensitivities.
https://www.healthdirect.gov.au/allergies-and-hypersensitivities