If you have allergies, pregnancy can make your symptoms worse. But you're right to worry about taking allergy medicine during pregnancy. Pregnant women shouldn't take some allergy drugs. Certain antihistamines, however, are safe.
free radical. (chemistry). An atom or a diatomic or polyatomic molecule which possesses one unpaired electron. Also known as a radical.ree radical. in chemistry, a molecule or atom that contains an unpaired electron but is neither positively nor negatively charged. Free radicals are usually highly reactive and unstable.
A free radical is a chemical with a very reactive chemical bond. The chemical bonds which hold atoms together to make molecules contain pairs of electrons. For example there are two electrons in each of the bonds holding the hydrogens to the oxygen in the water molecule.