Antihistamines

There are very limited studies for the use of antihistamines in breastfeeding, and data on long-term exposure is lacking. However, many can be used with caution while breastfeeding and with infant monitoring.

Non-sedating antihistamines

Recommendation

The preferred choice non-sedating antihistamines are cetirizine or loratadine. This is also supported by the British Society for Allergy and Clinical Immunology

Cetirizine and Loratadine

Cetirizine

There is extensive experience of use in breastfeeding, but limited published information. One study shows amounts in breast milk are very small which is expected based on its high protein binding. The milk level, following a 10mg dose, has been estimated as 1.77% of the weight-adjusted maternal dose. To date, no adverse effects have been reported in infants exposed to cetirizine via milk.

Loratadine

There is extensive experience of use in breastfeeding, but limited published evidence. Very small amounts have been found in milk, which is expected based on its high protein binding. One study, calculated the maximum dose an infant could receive via milk of loratadine plus desloratadine (its active metabolite) following a 40mg dose, as 1.1% of the weight-adjusted maternal dose.

In a survey of 51 breastfeeding mothers taking loratadine, only two mothers reported minor sedation in their infants and one reported decreased milk production. No other side effects were noted in any of the other breastfed infants.

Desloratadine, fexofenadine, levocetirizine

Recommendation

These can be used during breastfeeding when preferred choices are not suitable. They have not been studied directly in breastfeeding, but information can be extrapolated from other antihistamines. Therefore clinically significant amounts in milk are not expected.

Desloratadine

Desloraratadine is an active metabolite of loratadine. Data show that very small amounts of both loratadine and desloratadine are excreted in breast milk (1.1% of the weight-adjusted maternal dose).

Fexofenadine

Fexofenadine is an active metabolite of terfanadine. In four women given terfenadine, both terfenadine and fexofenadine milk levels were measured. Fexofenadine was calculated to be less than 0.45% of the weight-adjusted maternal dose. These negligible amounts would not be expected to cause adverse effects.

In another study, terfenadine was used by 25 breastfeeding mothers; mild irritability was reported in three breastfed infants.

Levocetirizine

Levocetirizine is an isomer of cetirizine, so they are almost identical in structure. Based on the evidence available and experience of use with cetirizine, small amounts in milk would be predicted and adverse effects are unlikely.

Acrivastine

Recommendation

Can be used during breastfeeding if preferred choices are not suitable. Acrivastine can commonly cause drowsiness when given directly, and the infant should be closely monitored for this if exposed through breast milk.

There is no published evidence on the use of acrivastine in breastfeeding. Based on its pharmacokinetic properties it is likely that it will be found in breastmilk in small to moderate quantities.

Sedating antihistamines

Recommendation

The preferred choice of sedating antihistamine is chlorphenamine due to extensive experience of safe use.

Hydroxyzine or promethazine can be used when breastfeeding with caution and close monitoring, if chlorphenamine is not suitable.

Considerations

If a sedating antihistamine is used, the infant is more likely to experience drowsiness and irritability, and close monitoring is required.

Use the lowest effective dose, for the shortest time possible; occasional doses are preferred.

Avoid use of other sedating medicines if possible.

The National Institute for Healthcare Excellence (NICE) advises avoiding sharing a bed with the infant when sedating medication has been used, due to the increased risk of sudden unexpected death in infancy.

Chlorphenamine

There is no published evidence regarding breast milk levels, but there is extensive experience of its use whilst breastfeeding. Based on its pharmacokinetic properties, it is likely to be found in small amounts in milk and its low oral bioavailability means clinically significant levels in the infant are not expected. It is therefore unlikely that the infant would have any side effects.

No adverse effects were reported in a prospective study where chlorphenamine was used by five breastfeeding mothers. Chlorphenamine can also be used therapeutically in infants from 1 month old.

Hydroxyzine

There is no published evidence regarding breast milk levels. Based on its pharmacokinetic properties it is likely to be found in breastmilk in small amounts. Hydroxyzine has been reported to cause adverse reactions in some infants, when exposed via milk, primarily sedation.

Promethazine

No published evidence is available for the use of promethazine in breastfeeding and milk levels have not been measured. Based on its pharmacokinetic properties, it is likely to be found in breastmilk in small amounts; low oral bioavailability will also limit the amount absorbed by the infant.

To date, no adverse effects have been reported in infants exposed via breastmilk.

Effect on breast milk production

There is conflicting data on the effect of antihistamines and breast milk production, and the evidence is very limited.

Antihistamines, used at normal therapeutic doses are unlikely to affect breast milk production, especially where lactation is established, i.e. after 6-8 weeks postpartum.

One small study, reported a possible increase in the time until milk secretion postpartum when promethazine (dose unknown) was given during labour. In another study, high doses of dexchlorphenamine or promethazine were reported to significantly reduce serum prolactin levels but did not influence suckling-induced prolactin release. One mother reported a reduction in milk production after taking 10mg of loratadine.

There have been no studies looking at other antihistamines, lower doses, or what effect any changes in prolactin might have on milk production.

Monitoring the infant

When using either a non-sedating or sedating antihistamine, the infant should be monitored for the following side-effects as a precautionary measure:

• drowsiness (for example, not waking to feed or sleeping for longer, and more often, than expected)
• irritability
• dry mouth
• changes in feeding (the infant should be feeding well and continue to gain weight as expected)

This will quickly pick up any potential issues. Usually, further investigation is required before attributing any side-effects to the medicine.

Younger, exclusively breastfed infants are at greater risk of getting side-effects. Using larger doses of antihistamine and for long courses also increases the risk.

Using sedating antihistamines increases the risk of drowsiness and irritability.

Patient Information

Patient information for specific antihistamines is available from the NHS Website: Medicines A-Z , including their use in breastfeeding.

Further Advice

Get in touch with the UK Drugs In Lactation Advisory Service (UKDILAS), our specialist breastfeeding medicines advice service, if:

• you need further advice
• there is an antihistamine which is not included
• the infant is unwell or premature
• a high dose of an antihistamine or multiple medicines are being taken

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