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Can Herbs Affect my Medication

There are some health problems where using herbs in medicinal quantities can be downright dangerous. Sometimes herbs can increase the effect of your drugs, in others they can block the absorption of your medication. Some nutrient supplements can be dangerous too. If you are taking any of these medications play it safe; check with an accredited clinical naturopath before you buy, and make sure all your health professionals know what you’re taking now.


– Exercise extreme caution using herbs where your medication has a ‘narrow therapeutic window’; that is, your medication may easily become dangerously toxic or totally ineffective with relatively small changes in blood concentrations. Common medications in this category include warfarin, immune-suppressing drugs and anti-HIV drugs

– Exercise extreme caution with herbs when you have impaired heart, liver or kidney function; if you are elderly, pregnant, or if you have a genetic disorder that disturbs your biochemical function.


BLOOD THINNERS such as Warfarin are a red flag for herbalists, and should only be taken under close supervision by an experienced clinical herbalist. These potent medications interact negatively with Bilberry, Coleus, Cranberry, Dan Shen, Devil’s Claw, Dong Quai, Garlic, Ginger and Meadowsweet, among others. You should also avoid fish oils or omega-3 supplements as these can thin your blood too far.

THYROID MEDICATION: Avoid Bladderwrack, Bugleweed, Celery Seed

HYPERTENSION (HIGH BLOOD PRESSURE) MEDICATION; Avoid Ginseng, and medicinal quantities of licorice. Confectionary licorice actually contains very little real licorice so that’s OK.

IMMUNE SUPPRESSING MEDICATION: Avoid echinacea, an immune stimulant, as it may reduce the effectiveness of your medication.

MEDICATION FOR YOUR MOOD: Avoid Ginkgo Biloba and St Johns Wort as they may increase or decrease the effectiveness of your medication.

HEART MEDICATION: Avoid Hawthorn. Be careful using laxative herbs with heart medication.


SLIPPERY ELM and MARSHMALLOW ROOT put a soothing coating on your gut lining – but they can also block the absorption of some drugs too.

PSYLLIUM HUSKS, although great for improving bowel health and boosting your fibre intake, can easily absorb your medication can carry it right out of your body. Take them well away from your medications.


Some medications can increase your body’s requirement for certain vitamins and minerals. Your nutritional naturopath can check reference texts to find out, or you can undergo functional pathology testing to discover what nutrients you need to replace.

Your local clinical herbalist can quicly check their latest reference texts to ensure your herbal remebies will not interfere with your medication.


Stop all natural and nutritional supplements seven days prior to surgery, and make sure your anaesthetist knows what you’ve been taking.

Communication is your key to staying safe; always inform your natural therapist about any medication you’re taking, and always tell your doctor about any natural remedies you are using. Stay safe; don’t self-prescribe!