Yes it is possible to be allergic to algae.
Yes, only if you are actually allergic to collagen. It is possible to be allergic to collagen.
No, it is not possible to be allergic to blood. Your immune system violently reacts to the allergens you are allergic to. If anyone were allergic to blood, they'd be dead by now. But it is possible to have a phobia of blood.
yes. i am allergic to the metal in the needles but the doctor does not know why.
Yes
Yes
no, are you crazy?
yes, it is possible to be allergic to anything.
Yes it is i have a friend who is allergic reaction to limestone dust
No, it is not possible to be allergic to the 'menstrual hormones'. If you are female then those hormones are present throughout your menstrual cycle so if you were allergic you'd see symptoms at all times. These are natural hormones and part of your body, you can't be allergic to yourself.
It is possible to be allergic to almost any substance. Only a doctor can tell you for sure, through proper testing.
i am allergic to pollen. So I can not smell flowers.