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Dr. Laura Pipher

Should you take “Diclectin” for your morning sickness?

Many women suffer from morning sickness (Read my blog post on morning sickness to learn more)

The management of women with nausea and vomiting of pregnancy depends upon(1)

  • The severity of symptoms
  • The impact of symptoms on your quality of life
  • The safety of treatment options for both mom and baby

Treatment approaches can include(1)

  • dietary/lifestyle changes
  • prescribed medication(s),
  • hospitalization for women with severe symptoms

Diclectin is a commonly known anti-nausea drug which is the combination of an antihistamine & vitamin B6 (Doxylamine & pyridoxine). Diclectin is also available as a sustained release drug known as “Doxylamine succinate-pyridoxine”. The mechanism of action of these two substances is that antihistamines block brain receptors that control nausea and vomiting, and pregnancy can cause vitamin B6 deficiency, so the combination of the two is theorized to be a good tool to ease morning sickness (1).

Taking note of current recommendations beyond diet and lifestyle treatment options,  the United States has determined Vitamin B6 should be prescribed as first-line pharmaceutical treatment for nausea and vomiting of pregnancy (2). The Society of obstetricians and gynecologists of Canada state Pyridoxine (vitamin b6)  monotherapy OR doxylamine/pyridoxine combination therapy is recommended as first line pharmaceuticals in treating nausea and vomiting of pregnancy due to their efficacy and safety, giving both vitamin b6 alone, and vitamin b6 + doxylamine an equal recommendation (3).

The most important question we need to ask when determining treatment options for pregnant women is

“Is it safe?”

Here is a summary of what we know:

  • 2015- study concluded Doxylamine succinate-pyridoxine hydrochloride delayed release combination is safe and well tolerated by pregnant women when used in the recommended dose of up to 4 tablets daily in treating nausea and vomiting of pregnancy (4).
  • A meta-analysis of controlled studies on outcome of pregnancies exposed to Bendectin (a previous brand-name doxylamine pyridoxine) reported no increase in the incidence of birth defects (4)
  • There is some conflicting evidence linking doxylamine-pyridoxine use to pyloric stenosis and childhood malignancies(5).
  • A randomized placebo-controlled trial found that doxylamine succinate 10 mg and pyridoxine 10 mg combination preparation administered in doses of two to four tablets daily was not associated with an increased risk of any adverse event and was well tolerated by women with nausea and vomiting of pregnancy (6)

It is important to also be mindful of  the “non medicinal ingredients” listed in the product . 

When it comes to non-medicinal ingredients, Diclectin, like many other pharmaceuticals and poor quality supplements, contains a very long list. A few ingredients to note include the food colourings and PEG 400.

PEG 400 is noted on another medication (vancomycin injection) which warns against use in pregnant women due to embryo fetal toxicity (10).  It is also noted that these effects are not noted using vancomycin alone (10). Another study evaluating blue no.2 (a colour in diclectin tablets) in rats found significantly reduced fertility indicators in the group fed the food colouring vs the controls (11).

Further, with any drug there are side effects to note.

Some side effects of doxylamine-pyridoxine include (7):

  • Dizziness
  • Drowsiness
  • Dry mouth
  • Fatigue
  • Stomach pain
  • Headaches
  • Irritability

So according to what we know, diclectin can be seen as “relatively safe”.  If this is the case,  the next question we need to ask is

“does it work”?

Here is a summary of what we know:

  • 2014 study concluded limited evidence that doxylamine-pyridoxine is more effective than pyridoxine alone and that there is stronger support for the safety of pyridoxine monotherapy than for the combination of doxylamine-pyridoxine during pregnancy (8)
  • 2020 UptoDate recommendations concluded
    • Doxylamine-pyridoxine was proven modestly effective for treatment of nausea and vomiting of pregnancy in a meta-analysis of placebo-controlled randomized trials, and appears to be more effective than either drug alone (1).
  • 2019 clinical trial demonstrated that the combination of doxylamine and pyridoxine produced small but statistically significant differences in symptoms and well-being compared with placebo. They further that there is not any high-quality evidence that shows that the combination of doxylamine and pyridoxine is more effective than other antiemetics (9).
  • In 2017, analysis suggests that while large studies have found no association between doxylamine-pyridoxine and birth defects, some smaller studies show an increased risk of pyloric stenosis and some childhood malignancies, although the overall risk of these remains small (9). Researchers concluded that there is not, at this time, clear evidence that the combination of doxylamine-pyridoxine is more effective in the management of NVP than pyridoxine alone (9).

So what are the other treatment options for your nausea and vomiting in pregnancy

Dietary changes

  • Eat as soon as you are hungry, avoiding an empty stomach which can aggravate nausea (keep snacks beside your bed so you can eat as soon as you wake up)(1)
  • Eat slowly and frequently throughout the day
  • Try eliminating triggers including:
    • Coffee
    • Spic foods
    • Very sweet foods or foods with high odour
  • Cold foods tend to be better tolerated than cooked foods as they contain less odour


  • Drink fluid 30 minutes before or after solids
  • Fluids are better tolerated if cold, clear, and carbonated or sour

Other lifestyle tips

  • Lying down soon after eating and lying on the left side are additional potentially aggravating factors because these actions may delay gastric emptying. Quickly changing position and not getting enough rest/sleep may also aggravate symptoms.
  • Brushing teeth after a meal, spitting out saliva, and frequently washing out the mouth can also be helpful.
  • Switching to a different toothpaste may help women for whom strong mint-flavored toothpaste is a trigger.
  • Taking prenatal vitamins before bed with a snack, instead of in the morning or on an empty stomach, may also be helpful (and make sure you have a prenatal containing iron glycinate or bisglycinate to reduce nausea)

Pyridoxine (vitamin B6) alone  —

  • Pyridoxine has been shown to improve nausea, has a good safety profile with minimal side effects, and is easy to obtain; therefore, we generally begin pyridoxine as the initial drug treatment.

Questions? Wanting to treat your pregnancy related nausea??

Send an email to drlaurapipher@gmail.com


1 https://www.uptodate.com/contents/nausea-and-vomiting-of-pregnancy-treatment-and-outcome/print

2 https://www.aafp.org/afp/2014/0615/p965.html

3 https://www.jogc.com/article/S1701-2163(16)39464-6/fulltext#sec5

4 https://pubmed.ncbi.nlm.nih.gov/25884778/?from_term=diclectin+safety&from_pos=3

5 https://pubmed.ncbi.nlm.nih.gov/24798673/

6 https://www.uptodate.com/contents/nausea-and-vomiting-of-pregnancy-treatment-and-outcome/print

7 https://dtb.bmj.com/content/57/3/38

8 https://pubmed.ncbi.nlm.nih.gov/24798673/

9 https://www.cfp.ca/content/cfp/63/1/13.full.pdf

10 https://www.accessdata.fda.gov/drugsatfda_docs/label/2019/211962s000lbl.pdf\

11 DOI: 10.1016/0278-6915(86)90351-0

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