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Pharmaceutical Milk Suppressants: What’s the Low Down?

Medicine cabinet filled with pharmaceuticals.

We know that some substances suppress milk production. Today, I’ll talk about pharmaceutical milk suppressants. But stay tuned for part 2 where I’ll address other milk suppressants, including herbs and herbaceous plants, as well as part 3 where I’ll go over social aspects.

Bromocriptine

I can practically hear you saying, “Bromo-whaaaaaat?

Bromocriptine (common trade name, Parlodel™) was originally developed for Parkinson’s disease. It works by blocking the release of prolactin from the pituitary gland.

Since milk production is directly related to prolactin, someone apparently assumed it would help to “dry up” the milk in mothers who had chosen to formula feed. Hence, it was prescribed off-label.

Around the early 1980s or so, we hospital nurses routinely administered bromocriptine to all formula-feeding mothers each morning in the immediate postpartum period. I wasn’t convinced that it had the intended effect, but I had an order for it, so I gave it.

However, the many side effects of this drug were concerning. Mild side effects, including headache, gastrointestinal problems, and drowsiness, could be unpleasant. Severe side effects, such as dangerously high blood pressure, cardiac arrhythmia, chest pain, coffee-grounds emesis, could be life-threatening.

To the best of my recollection, we stopped routinely giving this drug to postpartum mothers in early 1990s or so.

It’s still available in the US, and now is being used to control glycemic levels in adults.

Why am I bothering to mention this? Because I don’t know if it’s still being used to suppress lactation in other parts of the world, and the IBLCE Exam tests on global issues!

Hormonal-based products

When you think of possible pharmaceutical milk suppressants, immediately consider estrogen. Estrogen is the enemy of milk production.

Generally, oral contraceptives are made up of one estrogen and one of about eight different progesterone hormones.

Here is a long list of estrogen-containing oral contraceptives. (Scroll all the way down.)

To my knowledge taking a progestin-only oral contraceptive (OC) during lactation does not affect milk supply. This includes progestin-based pills (synthetic form of progesterone) meant for emergency contraception.

The “morning after” pills contain either levonorgestrel (Plan B One-Step™, Aftera, others) or ulipristal acetate (ella™).

Certainly, estrogen-based OCs suppress fertility. But medications to increase fertility could also be pharmaceutical lactation suppressants.

For example, clomiphene (CLOMID™), which works by tricking your body into thinking that your estrogen levels are low, could also reduce milk supply.

At this time, there are no studies on the effects of clomiphene in lactating women. However, Kalir and colleagues found it was the most effective method of suppressing milk in formula-feeding mothers. 

Depo-Provera (medroxyprogesterone)

Medroxyprogesterone acetate is an injectable birth control method that is given every 3 months. It works by preventing the growth and release of an egg each month.

I can’t begin to count the number of women, including IBCLCs, who have told me that “Depo” reduces milk supply. Yet, I can find no studies to substantiate that claim.

This drug has many possible maternal side effects, but, despite the anecdotal reports, a reduction in milk supply is not one of them. At least 6 studies have found that the use of intramuscular depot medroxyprogesterone acetate as a contraceptive beginning at 7 days postpartum or later either has:

If you’ve followed me for any length of time, you know that I’m committed to following the scientific studies. But here’s the catch.

Some years ago, when I was editor of Nursing for Women’s Health, I recognized that understanding research results before publication was a major part of my job. I got some good advice from Karen Haller, who was then the editor of Journal of Obstetric, Gynecologic and Neonatal Nursing.

Karen, an accomplished researcher and scholar herself, told me, “Be cautious about believing study conclusions when they don’t line in up with your clinical experience.”   

Now, I pass that advice on to you.

Decongestants

Decongestants simply relieve tissue congestion. That helps to reduce swelling in the nasal passageways, including the swelling caused by inflammation from an infection. Decongestants are known for their ability to relieve symptoms of the common cold.

Could a decongestant tablet such as pseudoephedrine (e.g., SUDAFED™) function as pharmaceutical milk suppressants?  Maybe.

The amount of the drug that enters into the mother’s milk is very small. Findlay’s study showed that the amount actually absorbed by the breastfed infant is about 0.4 to 0.6% of the maternal dose.

However, the amount in the milk apparently does not predict the effects on milk production.

Aljazaf and colleagues conducted a blind, placebo-controlled study with 8 lactating women who had taken a single 60-mg dose of pseudoephedrine. Within a 24-hour period, their milk supply had dropped by 24%.

The authors say that factors such as surface temperature etc., do not explain that drop in supply, but a drop in prolactin levels might. Note, too, that this was a very small study.   

Antihistamines

Unlike decongestants, antihistamines block a body chemical called histamine. Histamine is produced by the immune system. That means that antihistamines are more appropriate for relieving symptoms of an allergy — a condition where histamine is released.   

According to So and colleagues, “All antihistamines are considered safe to use during breastfeeding, as minimal amounts are excreted in the breast milk and would not cause any adverse effects on a breastfeeding infant.”

But as we know, safety is one issue; milk supply is something else.

At this time, we have no solid data that either first-generation or second-generation antihistamines are pharmaceutical milk suppressants

LactMed says: “Larger doses or more prolonged use may…decrease the milk supply, particularly in combination with a sympathomimetic such as pseudoephedrine or before lactation is well established.”

I’m suspicious. I ask myself: If an antihistamine would dry up secretions from your nose and eyes,

  • wouldn’t it dry up the natural fluids in joints? (Seems like it for my arthritic left knee!)
  • might it dry up fluids in your breasts?
  • Is it concerning that breast swelling and tenderness are listed as side effects of second-generation antihistamines?

It might be good to keep an eye for any milk supply issues with diphenhydramine (BENADRYL™) which is frequently given after epidural. Also, keep an eye out for any possible effects from cetirizine (ZYRTEC™) until we have more solid evidence.

Finally…

Stay tuned! In upcoming posts, I’ll talk about herbs and herbaceous plants and social aspects that can be lactation suppressants.

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