Doxylamine succinate – pyridoxine hydrochloride (Diclectin®)

Revised March 5, 2018

Section 1.1

Midwives may independently prescribe, order and administer this drug.

Doxylamine succinate competes with histamine for H1-receptor sites, which block chemoreceptor trigger zones, which control the symptoms of nausea and vomiting. The pyridoxine hydrochloride component is a vitamin which has antiemetic effects.

Indications and Clinical Use:

Nausea and vomiting in pregnancy (NVP) is a common medical condition of pregnancy, affecting up to 80% of all pregnancies. When fixed together in a delayed-release formula, doxylamine succinate and pyridoxine hydrochloride can be prescribed at the onset of symptoms to manage NVP. It can also be prescribed pre-emptively at the onset of pregnancy for multiparas at high risk of NVP.


Hypersensitivity to doxylamine, pyridoxine, or any component of the formulation; narrow-angle glaucoma; stenosing peptic ulcer; pyloroduodenal obstruction; bladder neck obstruction; or at risk for asthmatic attack.

Warnings and Precautions:

May cause CNS depression, including drowsiness, disorientation, dizziness, headache, paradoxical central nervous system stimulation, and vertigo, which may impair physical or mental abilities. Use with caution in patients with hypertensive disorders, asthma and thyroid dysfunction.




Category L3 – No Human Data – Probably Compatible

Doxylamine may be excreted in breast milk, and can result in sedative effects in nursing infants. Approved use of doxylamine and pyridoxine is limited to the prenatal period.

Adverse Reactions:

Palpitation, tachycardia, dizziness, drowsiness, headache, constipation, diarrhea, dry mucous membranes and epigastric pain.

Dosage and Administration:

10 mg of doxylamine combined with 10 mg of pyridoxine (delayed release formula) up to four tablets daily (one in the morning, one in the afternoon, two at bedtime). Take on an empty stomach. Titrate dose up to eight tablets a day as needed. Adjust schedule and dose according to severity of symptoms.


10-12 hours