PREGNANCY: Phenylephrine can cause birth defects in some animal species. Additionally, there have been associations between first trimester exposure to these medications and malformations, primarily minor malformations. Although one analysis found a correlation between guaifenesin use in the first trimester of pregnancy and an increased risk of hernia, others found no increased risk of malformations. Thus, guaifenesin/phenylephrine should be used in pregnancy only if the physician feels that the potential benefits outweigh the potential risks.
NURSING MOTHERS: Small amounts of phenylephrine is excreted in breast milk.
SIDE EFFECTS: Side effects of guaifenesin/phenylephrine and include stimulation of the nervous system leading to nervousness, restlessness, excitability, dizziness, headache, fear, anxiety, tremor, and even hallucinations and convulsions (seizures). Nausea, vomiting, and rash also occur.
Reference: FDA Prescribing Information
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