What are the side effects of the herbalean dietary supplement? There really are no major side effects. Matter of fact, we rarely get any complaints. But of course, like any other nutritional product, the herbalean dietary supplement may not agree with everyone. We occasionally receive comments from consumers stating this product make them feel jittery or this product give them heartburn. The jitteriness usually occurs because one's body is adjusting to the herbs. This usually goes away after a week or two. We usually find that those who get heartburn are individuals who have a history of heartburn. If you drink caffeine when taking the herbalean dietary supplement, you may experience a small amount of nausea. If this happens to you, try not to drink any caffeine within a couple of hours of taking these products.