In Adaptogens in Medical Herbalism, Donald R. Yance, CN, MH, RH(AHG) describes it as "extremely safe and well tolerated." In fact, it has been used in combination with some therapies to reduce negative effects. However, the Botanical Safety Handbook classifies astragalus as a Safety Class 1B herb, which means it may alter how medications affect the body. Interactions have not been proven, but they are biologically plausible. For example, due to its immune supporting properties, astragalus may counteract immune suppressing drugs. It may also increase the effect of blood pressure or blood sugar lowering medications. This safety rating only applies to the two varieties that are cultivated for therapeutic purposes - Astragalus membranaceus and Astragalus mongholicus. Certain varieties, such as A. lentiginosis or A. mollissimus (locoweed), are toxic and should be avoided.