- Ulex europaeus
- Ulmus americana
- Ulmus pumila
- Ulva compressa
- Ulva linza
- Uniola paniculata
- Urena lobata
- Urtica dioica
- Urtica urens
- Utricularia bifida
- Utricularia caerulea
- Utricularia foliosa
- Utricularia gibba
- Utricularia minor
- Utricularia subulata
- Utricularia vulgaris
- Uvularia perfoliata
- Uvularia sessilifolia
uphrasia alpina
- Eyebright (Euphrasia spp.)
- Usage: Used for eye problems.<wiki/List_of_medicinal_plants#cite_note-theherbbook-7">
- Harmful effects: Side effects may include confusion, headache, tearing, itching, redness, vision problems, sneezing, nausea, toothache, constipation, cough, trouble breathing, trouble sleeping (insomnia), sweating, and others.<wiki/List_of_medicinal_plants#cite_note-94">
Uncaria gambir
- Cat's claw (Uncaria spp. (approx. species))
- Claimed to: cure HIV, cancer, viral infections (such as herpes simplex), tremors, fever reduction, high blood pressure, Alzheimer's disease, chronic fatigue syndrome, and almost everything.
- Preparation: The inner bark and/or root of is/are used to make liquid extracts, capsules, and teas. Preparations can also be applied to the skin.
- Popularity: Cat's claw was ranked as the seventh most popular herb in U.S. sales in .<wiki/List_of_medicinal_plants#cite_note-52">
- Research: There is not enough scientific evidence to determine whether cat's claw works for any health condition.<wiki/List_of_medicinal_plants#cite_note-NCCAMCat-53"><wiki/List_of_medicinal_plants#cite_note-ACSCat-54">
- Beneficial effects:
- Small studies in humans have shown a possible benefit of cat's claw in osteoarthritis and rheumatoid arthritis, but no large trials have been done.<wiki/List_of_medicinal_plants#cite_note-NCCAMCat-53"><wiki/List_of_medicinal_plants#cite_note-ACSCat-54">
- In laboratory studies, cat's claw stimulates part of the immune system, but it has not been proven to reduce inflammation or boost the immune system in humans.<wiki/List_of_medicinal_plants#cite_note-NCCAMCat-53"><wiki/List_of_medicinal_plants#cite_note-ACSCat-54">
- The National Institute on Aging funded a study that looked at how cat's claw may affect the brain. Findings may point to new avenues for research in Alzheimer's disease treatment.<wiki/List_of_medicinal_plants#cite_note-NCCAMCat-53"><wiki/List_of_medicinal_plants#cite_note-ACSCat-54">
- Harmful effects:
- It may have an unwanted effect on blood pressure.