MedicalNewsToday also recommends using peppermint shampoos for their added relaxation and cooling benefits, and you can add a few drops of peppermint oil to regular shampoo to reap the same benefits. Excess peppermint oil exposure may result in acidity or nausea, and those who are pregnant, breastfeeding, or taking certain medications should consult a doctor first, as it may cause allergic reactions.