Johns Hopkins Health Alerts | Vision | Herbs and Your Eyes

8 herbs that could mean trouble for your eyes

Are you taking herbs or nutritional supplements for your eye health? If so, it’s important to be aware of the potential for side effects. Late last year, a study that included case reports submitted to the National Registry of Drug-Induced Ocular Side Effects highlighted several adverse ocular effects linked to the use of certain herbs and nutritional supplements.

The side effects of the herbs ranged from eye dryness to retinal hemorrhages and temporary loss of vision. In most cases, side effects were associated with higher doses of the particular herbs or supplement, and they cleared up once the person stopped taking the herbs in question. The study linked the following eight herbs and supplements to clinically significant ocular side effects:

1. Canthaxanthin. This carotenoid is found naturally in certain foods, particularly shellfish and chanterelle mushrooms. It’s used as a coloring to add an orange-red hue to foods, in cosmetics and in animal feed.
2. Chamomile (Matricaria chamomilla). Chamomile is often used to treat insomnia, indigestion, and skin problems.
3. Datura (Datura stramonium and D. wrightii). This supplement is sometimes used to treat asthma, bronchitis, and coughs.
4. Echinacea (Echinacea purpurea). This top-selling herb is used primarily to treat upper respiratory infections.
5. Ginkgo (Ginkgo biloba). This supplement is extremely popular, used to boost memory and to treat a number of conditions, including asthma, tinnitus, vertigo, and varicose veins.
6. Licorice (Glycyrrhiza glabra). Licorice is often used to treat a variety of conditions, including respiratory tract infections and constipation.
7. Niacin. In tablet form, niacin is used to treat cardiovascular and cerebrovascular disease. It also can be found in certain foods, including red meat.
8. Vitamin A. This vitamin is so important to health that you’d be hard-pressed to find a daily vitamin supplement without it. The daily recommended intake of vitamin A is 5,000 IU for men and 4,000 IU for women.

With some of these herbs, there are data on interactions with other medications or cautions about discontinuing them before surgery. For instance, the herb ginkgo interacts with haliperodol (Haldol), and it can increase the side-effects of antidepressants and certain antibiotics . And because it’s a blood thinner, you have a greater risk of bleeding when you take it with other blood thinners, such as aspirin or warfarin (Coumadin). Ginkgo also increases the risk of bleeding during surgery. As for licorice, do not take it if you are taking a diuretic, digoxin (Lanoxin and others), or insulin.

If you are facing eye surgery (or any other type of surgery), be sure to tell your physician which herbs you are taking. While the recommended time for discontinuing herbs before surgery varies, it’s safe to stop taking herbs and other supplements two weeks before surgery. That should allow enough time for the herbs to clear your body, thus decreasing the likelihood of any drug interactions or other side effects, including problems with anesthesia. The bottom line: Any product that has a therapeutic effect can also have a side effect. Herbs are no exception.