At face value, it is a strange request. But sedating antihistamines have long been known to have an anti-nausea effect on humans as H1 receptor histamine antagonists.

Doxylamine is recommended treatment for nausea and vomiting of pregnancy (see CPD article, Navigating nausea and vomiting during pregnancy).

However, if you look at a Schedule 3 box of doxylamine, you will not see any reference to use beyond the short-term treatment of primary insomnia. Additionally, some packs of doxylamine contain warnings not to use the medicine in pregnancy. So, what should you do?

Are pharmacists legally able to supply doxylamine for nausea and vomiting of pregnancy without a prescription?

The short answer is YES. There are no indication restrictions in the SUSMP for doxylamine.¹ So supply is considered off-label, but it is not illegal.

What are considerations for off-label supply?

Off-label (or off-license) use is using a medicine for a purpose not listed as one of the indications for use in the Australian Register of Therapeutic Goods (ARTG). This is legal, but the onus is on the prescriber and dispenser (in this case, the pharmacist is both) to justify the use of the medicine, and ensure the patient provides informed consent.²

In the case of doxylamine for nausea and vomiting of pregnancy, this is relatively straightforward given the large body of evidence,^3,4 and reputable clinical guidelines supporting its use.^3–5,9 Pharmacists should also communicate with patients that while the indication isn’t on the box, it is supported by evidence and guidelines.

What about the warning not to use doxylamine in pregnancy?

Doxylamine is Category A in the ABCDX classification system,¹⁰ and is considered safe for use in pregnancy. The TGA removed this warning as a requirement in late 2021.¹¹ So it is likely most of these warnings will disappear as new batches of stock are manufactured in updated packaging.

But aren’t pharmacists restricted to prescribing Pharmacist Only medicines to limited indications only?

The SUSMP does limit some (but not all) Schedule 3 medicines to specific medicines only – these are listed in the table below.

Table 1– Schedule 3 medicines with indication-specific listings¹

References

1. Therapeutic Goods (Poisons Standard – February 2024) Instrument 2024. TGA; 202. At: www.legislation.gov.au/F2024L00095/asmade
2. Day R. Off-label prescribing. Australian Prescriber. 36(December 2013):5–7.
3. Pregnancy Care Guidelines: Nausea and vomiting. Australian Government Department of Health and Aged Care. 2018. At: www.health.gov.au/resources/pregnancy-care-guidelines/part-i-common-conditions-during-pregnancy/nausea-and-vomiting
4. Taylor T. Treatment of nausea and vomiting in pregnancy. Australian Prescriber 2014;37(2). At: www.nps.org.au/assets/c54914225deb37a1-077be09b52f0-8b91fd8dbb1142caa58132e34b40b5466d337bd7268dda75dfae4a61d9f6.pdf
5. Nausea and vomiting during pregnancy | Therapeutic Guidelines. At: https://tgldcdp.tg.org.au/viewTopic?etgAccess=true&guidelinePage=Gastrointestinal&topicfile=c_GIG_Gastro-oesophageal-reflux-in-adultstopic_1&guidelinename=auto&sectionId=c_GIG_Nausea-and-vomiting-during-pregnancytopic_5#c_GIG_Nausea-and-vomiting-during-pregnancytopic_5
6. Nausea and Vomiting in Pregnancy and Hyperemesis Gravidarum. NSW Health Guideline. 2022;30.
7. Guideline: Nausea and Vomiting – Pregnancy. The Royal Women’s Hospital, Melbourne. 2020.
8. Tan A, Foran T, Henry A. Managing nausea and vomiting in pregnancy in a primary care setting. Australian Family Physician 2016 Aug;45(9):169.
9. Nausea and Vomiting in pregnancy and Hyperemesis Gravidarum. SA Health Perinatal Practice Guideline. 2020.
10. eMIMS. 2024 [cited 2023 Nov 20]. At:www.emims.com.au/Australia/membership/index/?returnUrl=https%3a%2f%2fwww.emims.com.au%3a443%2fAustralia%2fdrug%2fsearch
11. Administration (TGA) TG. Medicines Advisory Statements Specification updates | Therapeutic Goods Administration (TGA). 2022. At: www.tga.gov.au/news/news/medicines-advisory-statements-specification-updates