In recent years, as public awareness of maternal and infant health continues to grow, medication safety during breastfeeding has become one of the primary concerns for new mothers. Many people believe that "no medications should be taken while breastfeeding," choosing to endure illness without treatment. Others assume that only a negligible amount of medication passes into breast milk and therefore take medications without concern. In reality, both views are overly simplistic.

Whether a medication can be safely used during breastfeeding depends primarily on the extent to which it is excreted into breast milk, the infant's absorption of the drug, the drug's half-life, and the infant's age and health status. Most commonly used medications are not absolutely contraindicated during lactation. However, some drugs may adversely affect infant development or cause serious adverse reactions, requiring temporary interruption or complete cessation of breastfeeding. Understanding which medications require caution is essential for ensuring the safety of both mother and child.

 

I. Why Is Extra Caution Needed When Taking Medications During Breastfeeding?

Breast milk is the ideal natural source of nutrition for infants, but a portion of medications taken by the mother may pass into breast milk and subsequently be ingested by the infant.

Although the amount transferred into breast milk is generally low (typically less than 1%–10% of the maternal dose), newborns—particularly preterm infants—have immature hepatic and renal function and limited drug metabolism. As a result, even small amounts of medication may have clinically significant effects.

Therefore, international guidelines typically evaluate the safety of medications during breastfeeding based on the following factors:

● Relative Infant Dose (RID)

● Drug half-life

● Oral bioavailability in the infant

● Infant age and overall health status

● Availability of documented adverse reaction reports

Therefore, whether a medication can be used during breastfeeding cannot simply be answered with a "yes" or "no." Each medication should be evaluated individually.

 

II. Which Medications Are Generally Contraindicated During Breastfeeding?

The following medications are generally considered high-risk because they may pose significant risks to the infant. Breastfeeding should usually be avoided or temporarily discontinued during treatment.

1. Antineoplastic (Chemotherapy) Drugs

These are among the clearest contraindications during breastfeeding.

Examples include:

● Cyclophosphamide

● Methotrexate

● Doxorubicin

● Cisplatin

● Paclitaxel

These agents inhibit cell division and may theoretically impair the infant's bone marrow, immune system, and normal growth and development. Therefore, breastfeeding is generally discontinued throughout chemotherapy.

2. Radiopharmaceuticals

Radioactive isotopes used in nuclear medicine for diagnostic imaging or therapy include:

● Iodine-131 (I-131)

● Gallium-based imaging agents

● Certain technetium-labeled radiopharmaceuticals

The recommended duration of breastfeeding interruption varies depending on the specific radionuclide. Some require temporary cessation for several days, while others may require permanent discontinuation of breastfeeding for the current infant. Recommendations from nuclear medicine specialists should always be followed.

3. Ergot Alkaloids

Examples include:

● Ergotamine

● Dihydroergotamine

These medications are primarily used to treat migraine headaches.

Potential effects include:

● Suppression of lactation

● Vomiting in infants

● Diarrhea

● Vasoconstriction

These drugs are generally not recommended during breastfeeding.

4. Lithium

Lithium is commonly prescribed for bipolar disorder.

Lithium readily passes into breast milk, and infants have limited ability to eliminate the drug. Potential adverse effects include:

● Excessive drowsiness

● Hypotonia

● Cardiac rhythm abnormalities

● Thyroid dysfunction

Therefore, most clinical guidelines recommend avoiding breastfeeding during lithium therapy. If lithium treatment is essential, close monitoring by a specialist is required.

 

III. Which Common Medications Require Temporary Interruption of Breastfeeding?

Some medications are not absolutely contraindicated but generally require temporary suspension of breastfeeding during treatment.

1. Certain Antiviral Medications

For example:

● Ribavirin

Because of its potential reproductive toxicity, breastfeeding is generally not recommended during ribavirin therapy.

2. High-Dose Contrast Imaging Procedures

Most iodinated CT contrast agents and gadolinium-based MRI contrast agents are excreted into breast milk in extremely small amounts, and breastfeeding usually does not need to be interrupted.

However, certain specialized imaging procedures may require temporary cessation of breastfeeding. Recommendations provided by the imaging center should be followed.

3. Certain Psychiatric Medications

For example:

● Clozapine

Potential effects in breastfed infants include:

● Sedation

● Agranulocytosis

● Poor sucking ability

Breastfeeding is generally not recommended during clozapine treatment, or temporary interruption may be advised.

 

IV. Which Medications Can Generally Be Used With Caution?

In fact, most medications commonly used by breastfeeding mothers can be continued under appropriate medical supervision.

Examples include:

① Antipyretic and Analgesic Medications

Generally considered safe:

● Acetaminophen (Paracetamol)

● Ibuprofen

Both drugs are transferred into breast milk in only minimal amounts and are recommended by most international guidelines as first-line options for pain relief and fever reduction during breastfeeding.

② Antibiotics

Most are considered compatible with breastfeeding, including:

● Penicillins

● Amoxicillin

● Cephalosporins

A small number of infants may experience mild diarrhea or oral thrush, but these medications are generally regarded as safe.

③ Antihypertensive Medications

Commonly considered compatible with breastfeeding:

● Labetalol

● Nifedipine

● Enalapril (for mothers of full-term infants during the postpartum period)

④ Antidiabetic Medications

Including:

● Insulin

● Metformin

Both are excreted into breast milk in very small amounts and have extensive clinical safety experience during breastfeeding.

⑤ Asthma Medications

For example:

● Salbutamol inhaler

● Budesonide inhaler

Because these medications primarily act locally in the airways and have minimal systemic absorption, they pose very little risk to breastfed infants.

 

V. How Can Medication Exposure to the Infant Be Minimized?

For medications considered compatible with breastfeeding, the following strategies may further reduce infant exposure:

● Whenever possible, choose medications with well-established safety data during lactation.

● Use the lowest effective dose for the shortest possible treatment duration under medical supervision.

● For certain short half-life medications, take the medication immediately after breastfeeding so that drug concentrations are lower by the next feeding.

● Avoid combining multiple medications or prolonged self-medication without medical advice.

● If the infant develops excessive sleepiness, feeding difficulties, diarrhea, rash, irritability, or poor weight gain, seek medical attention promptly.

 

VI. Common Misconceptions About Medication Use During Breastfeeding

Misconception 1: All medications enter breast milk, so no medications can be taken while breastfeeding.

In reality, most commonly used medications pass into breast milk only in very small amounts and can be safely used under medical supervision.

Misconception 2: Herbal medicines and dietary supplements are always safer.

Natural does not necessarily mean safe. Many herbal medicines and dietary supplements lack adequate safety data during breastfeeding, and some ingredients may reduce milk production or pose potential risks to infants. Therefore, they should also be used cautiously.

Misconception 3: Breastfeeding can resume immediately after stopping medication.

Different medications remain in the body for different lengths of time. Whether breastfeeding should be interrupted—and for how long—depends on the drug's half-life and professional medical recommendations rather than personal judgment.

 

Conclusion

The principle of medication use during breastfeeding is not "absolute avoidance," but rather selecting the safest treatment option for both mother and infant after carefully balancing maternal therapeutic benefits against potential risks to the infant. For the vast majority of common illnesses, relatively safe alternative medications are available. However, high-risk medications such as antineoplastic agents, radiopharmaceuticals, and lithium require strict adherence to medical advice, and temporary or permanent cessation of breastfeeding may be necessary.

If treatment requires innovative medications that have not yet been approved domestically or are prescribed for special indications, breastfeeding safety should be carefully evaluated under the guidance of a specialist, with reference to international prescribing information and the latest evidence-based medical literature to develop an individualized treatment plan.

As a platform dedicated to global innovative pharmaceutical services, DengYueMed continuously monitors developments in innovative medicines and maternal medication safety. We provide professional pharmaceutical services including innovative drug information, overseas medication consultation, drug source verification, and compliant access to international pharmaceutical channels, helping patients stay informed about global therapeutic advances and make more scientific and evidence-based medication decisions while safeguarding maternal and infant health.