People who should not take Zantac are those who are allergic to it, according to Drugs.com. Patients who take triazolam should also avoid Zantac. People who suffer from kidney or liver disease or porphyria need to ask their doctor if it is safe for them to take Zantac. The drug does not seem to be harmful to the fetus, but it passes into breast milk.
A person who has phenylketonuria might also wish to avoid the type of Zantac that comes in effervescent tablet form, says Drugs.com. Phenylketonuria, or PKU, is an inherited disorder where the body cannot use an amino acid known as phenylalanine, according to MedlinePlus. This is because they are born without the enzyme phenylalanine hydroxylase. Without this enzyme, phenylalanine builds up in the body to the point where it damages the central nervous system. The effervescent Zantac tablet has phenylalanine, and a person with PKU may not be able to tolerate it.
Porphyria is the name of a family of inherited diseases where porphyrin builds up in the patient's body, according to Mayo Clinic. Porphyrin is a chemical that's necessary for hemoglobin to function properly. Zantac can sometimes cause acute porphyria, which affects heme production.
Patients who are taking Zantac should avoid alcohol and check with their doctors if they are taking another medication or supplement, says Drugs.com.