I have a white oval pill with the letter C on it, Can anyone help me identify it?

Might also be Cetirizine Hydrochloride 10mg, which is a generic version of Zyrtec available over-the-counter for the treatment of allergies.

https://www.drugs.com/imprints/c-20338.html

By the description you give, I have found a match but it does not have an image.

Generic Name: carglumic acid

Pill imprint C has been identified as Carbaglu 200 mg.

Carbaglu is used in the treatment of hyperammonemia and belongs to the drug class miscellaneous uncategorized agents. Risk cannot be ruled out during pregnancy.

Carbaglu 200 mg is not subject to the Controlled Substances Act.

Click on the link as for you to read the description of the pill:

https://www.drugs.com/imprints/c-15737.html

If it is not the one , take it to your local pharmacy, perhaps the Pharmacist can ID it.

Take care,

maso.-