The US FDA has assigned the pregnancy category B status to Benadryl, which means that it is considered safe to use, as there are no known side effects. However, your doctor will be the best person to judge whether or not you should take Benadryl while you are pregnant. He will also decide on the quantity of intake.
Human carcinogen -- Benzene: Benzene is a chemical deemed to be carcinogenic to humans. The carcinogenicity of the substance may be influenced by the nature (e.g. inhalation, ingestion, skin contact), duration and level of exposure. Benzene exposure is associated mainly with an increased risk of developing leukemia or lymphoma.
Benzene is an organic chemical compound sometimes known as benzol. It has a particularly sweet smell and is a colorless, flammable liquid. Benzene is a major industrial solvent and is used in the production process of plastic, oil, synthetic rubber and many dyes.d. Commonly, benzene is used as an additive to other chemicals. It is used to make styrene, which is used to make plastics and polymers, and in the manufacturing process of nylon. Small amounts are used in the manufacturing processes of drugs, detergents, pesticides and explosives.