I just looked at "A Review of the Medical Benefits and Contradictions to
Breastfeeding in the United States" by Ruth Lawrence.  It is a wonderful
pamphlet published under the auspices of the US Dept of Health and Human
Services.  It is either free or very low cost and something everyone
should have.  (Info probably applies well to all industrialized nations)
Information is presented succinctly and clearly.

On page 31 there is a chart:
Summary of Medical Contraindications to Breastfeeding in the United
States.  (This is not all of it - I left off some conditions and the
whole class of environmental contaminants)

Problem                         OK to Bf in US  Conditions
Acute infections diseases       Yes
HIV                             No
Active TB                       Yes             After 2 weeks of treatment
Hep. A,B,C,                     Yes
Venereal warts                  Yes
Herpes viruses:
        cytomegalovirus         Yes
        herpes simplex          Yes             Except if lesion on breast
        varicella-zoster        Yes             When past infectious stage
        Epstein-Barr            Yes
Toxoplasmosis                   Yes
Mastitis                        Yes
Lyme disease                    Yes             Once treatment starts
HTLV-1                          No

Medication/Prescription drugs
Antimetabolites                 No
Radiopharmaceuticals
        diagnostic              Yes             After compound clears plasma
        therapeutic             No
Drugs of abuse                  No              Except cigarettes, alcohol
Other medications               Yes             Drug-by-drug assesment


If the chart doesn't come through properly - strep is certainly not on
this list as a contraindication.  Penicillin is also generally considered
safe, although not specifically mentioned here.

Sarah Friend Barnett   LLLL, IBCLC
Bronx (New York City), NY  -  [log in to unmask]
" You are not obliged to finish the task,
 neither are you free to neglect it."       R. Tarfon

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