Breastfeeding and podiatry – Local anaesthetics and liquefied phenol for ingrowing toenails

This information can also be viewed as a PDF by clicking here.

The information provided is taken from various reference sources.  It is provided as a guideline.  No responsibility can be taken by the author or the Breastfeeding Network for the way in which the information is used.  Clinical decisions remain the responsibility of medical and breastfeeding practitioners.  The data presented here is intended to provide some immediate information but cannot replace input from professionals.

Ingrowing toenail surgery involving local anaesthetic and phenol or sodium hydroxide does not necessitate interruption of breastfeeding

The available research evidence of safety from studies, for the administration of phenol or sodium hydroxide to ingrowing toenails during lactation is limited. However, from the study of pharmacokinetic data, the risk is low and the advantages of ongoing breastfeeding are greater. The risk from the use of local anaesthetics during lactation is negligible.


The passage of phenol into breastmilk has not been extensively studied. However, absorption of topical products into breastmilk is restricted (1) so the limited quantity of liquid phenol applied to the nailbed during the procedure is unlikely to penetrate into breastmilk in any significant quantities. The passage across the different biological membranes/systems which have to be traversed before absorption from breastmilk, suggest that the application is unlikely to affect the breastfed baby.

The EPA (US Environmental protection agency) (2) has determined that exposure to phenol in drinking water at a concentration of 6 milligrams per litre (mg/L) for up to 10 days is not expected to cause any adverse effects in a child.

Phenol is considered to be quite toxic to humans via oral exposure but studies represent chronic rather than single episode exposure (3). Solutions containing phenol should not be applied to large areas of skin or wounds since sufficient phenol may be absorbed to give rise to toxic symptoms. This is not applicable in the use in the treatment of ingrowing toe-nails.

There is no information on levels of phenol in human breast milk (4). No mention is made of use in lactation in the Cochrane reviews (5,6).

Sodium hydroxide

Currently phenol which has always formed the mainstay of practice, has been difficult to source so sodium hydroxide is largely being used instead. Just as with phenol there is an absence of research studies but topical absorption is very unlikely in the quantities used during the procedure.

Acetic Acid

Acetic acid may also be used by the practitioner to neutralise the products applied. Similarly, topical absorption is unlikely and breastfeeding can continue as normal.

Local Anaesthetics

Local anaesthetics are poorly bio available and have a short half- life and should not preclude normal breastfeeding after the procedure. They are widely used in other areas of medicine during breastfeeding e.g. dental procedures, suturing post-natally and in other surgical procedures. (5,6,7,8,9) .

This information was accepted by the College of Podiatry in March 2017 and forms part of their current guidelines.


  1. Stoukides C Topical Medications and Breastfeeding. J Hum Lact 1993; 9(3) :185-7)
  2. EPA Public Health Statement 2016
  3. EPA Hazard Study Phenol 2016
  4. Toxicological Profile For Phenol
  5. Cochrane review. Treatment for ingrowing toenails 2012
  6. Cochrane clinical answers What are the benefits and harms of interventions for ingrowing toenails?
  7. Hale T Medications and Mothers Milk
  8. Jones W Breastfeeding and Medication Routledge 2018
  9. Lactmed ToxNet database

©Dr Wendy Jones MBE, MRPharmS and the Breastfeeding Network May 2021