Safety advice when taking
St John's Wort

Always read the patient information leaflet inside each box of St John's Wort, whether it is a tablet or a liquid.

General precautions

St John's Wort is intended for relief of symptoms of slightly low mood and mild anxiety. Patients with signs and symptoms of depression should seek medical advice for appropriate treatment. If your symptoms have not started to clear up within six weeks you should see a qualified healthcare professional.

In very rare cases, particularly in light-skinned persons, sun burn type reactions on skin areas exposed to strong sunlight may occur due to photosensitisation by St John’s wort. Persons using this product should avoid excessive sunbathing or the use of sunbeds or solariums. 

This product should be discontinued at least 10 days prior to any surgery due to the potential for interactions with medicinal products used during general and regional anaesthesia.

Not recommended for use in pregnancy or during breastfeeding due to a lack of case studies and safety data.

Drug interactions

Substances in St John’s wort (Hypericum perforatum) have been shown to induce the cytochrome P450 isoenzymes CYP1A2, CYP2C19, CYP2C9 and CYP3A4 as well as the transport protein P-glycoprotein. This results in pharmacokinetic interactions with a large number of medicines leading to a potential decrease in the effectiveness of those medicines. 

The concomitant use of ciclosporin, tacrolimus for systemic use, Amprenavir, indinavir and other protease inhibitors, irinotecan and warfarin is contraindicated. 

Special care should be taken in case of concomitant use of all drug substances the metabolism of which is influenced by CYP1A2, CYP3A4, CYP2C9, CYP2C19 or P-glycoprotein (e.g. amitriptyline, fexfenadine, benzodiazepines, methadone, simvastatin, digoxin, finasteride), because a reduction of plasma concentration is possible. 

Users of oral contraceptives taking St John’s wort (Hypericum perforatum) may experience intracyclic menstrual bleeding and risk of contraception failure is increased. 

Clinically significant pharmacodynamic interactions have also been identified with the SSRI antidepressants, and the triptan group of medicines used to treat migraines. Due to the increased risk of undesirable effects associated with these interactions this product should not be used concomitantly with these types of medicines. 

Therefore St John's Wort should not be taken concomitantly with the medicines below. 

Anaesthetics /pre-operative medicines 

fentanyl, propofol, sevoflurane, midazolamReduced blood levels with risk of therapeutic failure. Based on the elimination half-lives of hypericin and hyperforin this product should be discontinued at least 10 days prior to elective surgery. 

Analgesics 

tramadolReduced blood levels with risk of therapeutic failure. Do not take with this product. 

Antianginals 

ivabradineReduced blood levels with risk of therapeutic failure. Do not take with this product. 

Anti-arrhythmics 

amiodaroneReduced blood levels with risk of therapeutic failure. Do not take with this product. 

Antibacterials 

erythromycin, clarithromycin, telithromycinReduced blood levels with risk of therapeutic failure. Do not take with this product. 

Anticoagulants 

warfarin, acenocoumarolReduced anticoagulant effect and need for increased dose Do not take with this product. 

Antidepressants 

Tricyclics eg. amitriptyline, clomipramine MAOIs eg. moclobemide SSRIs eg. citalopram, escitalopram, fluoxetine, fluvoxamine, paroxetine, sertraline, Others eg. duloxetine, venlafaxineIncreased serotonergic effects with increased incidence of adverse reactions. Do not take with this product. 

Antiepileptics 

All drugs in this class including: carbamazepine, phenobarbitone, phenytoin, primidone, sodium valproateReduced blood levels with increased risk of frequency and severity of seizures. Do not take with this product. 

Antifungals 

itraconazole, voriconazoleReduced blood levels with risk of therapeutic failure. Do not take with this product. 

Antimalarials 

artemether lumefantrineReduced blood levels with risk of therapeutic failure. Do not take with this product. 

Anti-parkinsons 

rasagilineReduced blood levels with risk of therapeutic failure. Do not take with this product. 

Antipsychotics 

aripiprazoleReduced blood levels with risk of therapeutic failure. Do not take with this product. 

Antivirals 

HIV protease inhibitors: amprenavir, atazanavir, darunavir, fosamprenavir, indinavir, lopinavir, nelfinavir, ritonavir, saquinavir, tipranavir  Reduced blood levels with possible loss of HIV suppression. Do not take with this product. 

HIV non-nucleoside reverse transcriptase inhibitors: efavirenz, nevirapine, delavirdine Reduced blood levels with possible loss of HIV suppression Do not take with this product. 

Anxiolytics 

buspironeIncreased serotonergic effects with increased incidence of adverse reactions. Do not take with this product. aprepitantReduced blood levels with risk of therapeutic failure. Do not take with this product. 

Barbiturates 

butobarbital, phenobarbitalReduced blood levels with risk of therapeutic failure. Do not take with this product. 

Calcium channel blockers 

amlodipine, nifedipine, verapamil, felodipineReduced blood levels with risk of therapeutic failure. Do not take with this product. 

Cardiac glycosides 

digoxinReduced blood levels and loss of control of heart rhythm or heart failure. Do not take with this product. 

CNS Stimulants 

methyl phenidateReduced blood levels with risk of therapeutic failure. Do not take with this product. 

Cytotoxics 

irinotecan, dasatinib, erlotinib, imatinib, sorafenib, sunitinib, etoposide, mitotaneReduced blood levels with risk of therapeutic failure. Do not take with this product. 

Hormonal contraceptives 

Oral contraceptives, Emergency Hormonal Contraception, Hormonal implants, injections, Transdermal patches, creams etc. Intra-uterine devices with hormones Reduced blood levels with risk of unintended pregnancy and breakthrough bleeding. Do not take with this product.

 Hormone Replacement Therapy 

Oral trandermal patches, gels, vaginal ringsReduced blood levels with risk of therapeutic failure. Do not take with this product. 

Hormone antagonists 

exemestaneReduced blood levels with risk of therapeutic failure. Do not take with this product. 

Diuretics 

eplerenoneReduced blood levels with risk of therapeutic failure. Do not take with this product. 

5HT agonists 

almotriptan, eletriptan, frovatriptan, naratriptan, rizatriptan, sumatriptan and zolmitriptanIncreased serotonergic effects with increased incidence of adverse reactions. Do not take with this product. 

Immunosuppressants 

ciclosporin, tacrolimusReduced blood levels with risk of transplant rejection. Do not take with this product. 

Lipid regulating drugs 

simvastatin, atorvastatinReduced blood levels with risk of therapeutic failure. Do not take with this product. 

LithiumReduced blood levels with risk of therapeutic failure. Do not take with this product. 

Proton pump inhibitors 

lansoprazole, omeprazoleReduced blood levels with risk of therapeutic failure. Do not take with this product. 

TheophyllineReduced blood levels and loss of control of asthma or chronic airflow limitation. Do not take with this product. 

Thyroid hormones 

thyroxineReduced blood levels with risk of therapeutic failure. Do not take with this product. 

Oral hypoglycaemic drugs 

gliclazideReduced blood levels with risk of therapeutic failure. Do not take with this product.

© Napiers Herbals Ltd 2014 • Edinburgh and Glasgow • Herbalists and Medical Botanists since 1860
'
Offers Banner