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Dave and other members of the bpacnz team answer your clinical question
“I have a patient who has breakthrough bleeding on Estelle 35, when she has previously had no problems with this.
She has also started fluoxetine 40mg recently. I noticed on the interactions list that it can interact with St John’s
Wort. Is the same true with fluoxetine? I have checked for other causes as well, but wondered if the fluoxetine could
be to blame.”
St John’s Wort can interact with oestrogens (i.e the ethinyloestradiol component of Estelle 35) by inducing their
metabolism and reducing plasma concentrations. This could lead to irregular menstrual bleeding. However, fluoxetine does
not have the same effect and does not interact with oestrogens in this way.
I have looked into whether fluoxetine (and the SSRIs in general) can cause breakthrough bleeding or menstrual bleeding
irregularities. A search of the product information and Medline via PubMed revealed nothing of relevance or interest.
Before discounting fluoxetine as a potential cause of this problem it is worth noting that SSRIs can cause bleeding
disorders in general by virtue of their antiplatelet effect. A range of disorders have been reported from easy bruising,
ecchymoses right through to gynaecological or GI haemorrhage. This may be an unlikely cause but it may be worth considering
especially if your patient has other signs of bleeding such as bruising or bleeding gums.
Camphor in pregnancy
“I have a patient in early pregnancy who took camphor for a week to aid giving up smoking. This was recommended
by the health shop. Is it safe? She has now stopped it.”
Although camphor is not recommended in pregnancy it was presumably at a low dose for a short time and is unlikely to
However, camphor is toxic and can cause death if taken in sufficient quantities.1,2 A toxic dose in an adult
would be about 2 g and 4 g or more may be a lethal dose.3 Nicobrevin is one commercial smoking cessation product
that contains 10mg of camphor. Camphor crosses the placenta however the rate and extent of transfer is unknown.2
Camphor is not recommended during pregnancy and there has been one reported case of fetal death when a pregnant woman
had accidently ingested a toxic dose of camphor.1,2
See smoking cessation article for advice on smoking cessation therapy in pregnant women.
- Briggs GG, Freeman RK, Yaffe SJ. Drugs in Pregnancy and Lactation: A Reference Guide to Fetal and Neonatal Risk. (6th
Edition) Philadelphia: Lippincott Williams & Wilkins. 2002
- Committee on Drugs: American Academy of Pediatrics. Camphor: Who Needs it?. Pediatrics 1978; 62(3): 404-406
- Moffat AC, Osselton MD, Widdop B (eds), Clarke’s Analysis of Drugs and Poisons. Pharmaceutical Press. Electronic
version, (Edition 2006)
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