Arnica has some safety precautions that we haven’t really been concerned with for many of the other herbs in our apothecary – for example, plantain, calendula, yellow dock, and dandelion are all pretty safe both internally and externally. Arnica should only be used externally, should only be used on closed wounds, and should only be used for a short time – up to about six weeks. These criteria make arnica perfect for temporary issues, like
bumps with pain and swelling
sprains with pain and swelling
bruises
sore or strained muscles
How does arnica work?
Arnica’s therapeutic action comes from its ability to support vasodilation in areas where it is rubbed on the skin. This helps to increase blood flow, which – as mentioned in this article on ice vs. heat therapy for injuries – brings nutrients needed to support healing to the affected area while also carrying away waste from the damaged area.
Herbalist Kami McBride even uses arnica preventatively. If she knows she will be using her muscles more than normal, like for a particularly long hike, she will slather arnica-infused oil all over her body beforehand to reduce muscle soreness the next day. (Source: Handcrafted Healing Herbal Oils Course)
Uses of arnica (And where to buy it)
Arnica flowers are most often used as an infused oil or cream
Something to keep in mind when purchasing arnica is that because arnica it’s listed as a species to watch by United Plant Savers (not currently endangered but potentially at risk), it’s important to purchase arnica that is specifically designated as sustainably harvested or cultivated. Sustainably harvest plants are typically gathered from the wild, but some is left behind to ensure that the species remains healthy. Cultivated arnica is grown on farms that have dedicated themselves to making it available for therapeutic use. Purchasing cultivated herbs is a great way to support farmers and the continued production of valuable herbs.
A teeny tiny jar of arnica cream can cost more than $30, but learning to make your arnica oil and/or arnica cream is super cost effective, and very handy for those bumpy bruisy situations.
Contraindications for arnica
Arnica is an herb to respect. Internally, it can damage many organs, and externally it can cause irritation in some people. It should never be used in the following scenarios:
Internal use
Externally on open wounds
Long-term (more than six weeks on a daily basis)
Before surgery
With blood thinners
It is an aster, so be careful if you have a ragweed allergy. Also, if you use it according to recommended guidelines and you experience irritation, discontinue use and switch to another herb.
Is arnica safe for pregnancy and/or nursing?
In addition to the safety precautions above, the Botanical Safety Handbook, 2nd edition, mentions overdoses of arnica infusions and flower tinctures have led to miscarriage. They reported no studies confirming the safety of arnica during lactation. Aviva Romm, MD, RH (AHG), and midwife recommends topical use of arnica for backaches, sore muscles, sore joints, and/or breast pain during pregnancy, even daily, in The Natural Pregnancy Book, 3rd edition. (Keep in mind, of course, that in general it is only used daily for up to six weeks.)