I use contact lenses and sometimes my eyes get red.i'm also allergic.shall i use eye drops, antiallergenics or take off the lenses?

Take out contacts: In order to put in anti-allergy eye drops, you need to take out your lenses anyway, so take them out for awhile, as soon as practically possible, when the eyes become red. Redness means inflammation. It's really hard to tell if there is one cause or several. The contact itself is a foreign body, and if you are allergic, you can even be allergic to drops, so have your eye doctor check you & advise.

Allergies: All of your proposed treatments should help. Frequent artificial tears, cool compresses, limitation of contact wear and/or switch to daily contact lenses, and topical and/or allergy meds should be helpful.