Although polynucleotides are well tolerated by most patients and are suitable for all skin types, including sensitive skin, they are derived from fish, therefore are not appropriate for vegans. Allergic reactions are very unlikely as the particles of DNA are highly purified, so it can be safely injected into those who have allergies, including seafood allergies, with clinical trials reporting no allergic reactions to date. Polynucleotides are not suitable for patients who are pregnant or intending pregnancy, or who are breastfeeding.