Here are things you may want to avoid when you have POTS because they can make you're symptoms worse.
Alcohol lowers lowers blood pressure and causes dehydration. If you have POTS, you may have low blood pressure and low blood volume, which will only be made worse if you are dehydrated.
Avoid Large Meals
May POTS patients, including yours truly, feel a worse about a hour after eating a large meal. This could be from any number of things, but doctors have found that many POTS patients have post-prandial hypotension. Post-prandial hypotension is a drop in blood pressure large enough to cause you to feel dizzy/faint/lightheaded that is caused by blood pooling in your abdominal region, which happens when you digest food. The more food you eat at once, the more blood is needed to help digest the food, the dizzier you can feel. It doesn't help if you already have low blood pressure to begin with either. You can minimize post-pradial hypotension by eating smaller meals more often throughout the day and by wearing compression stockings that come all the way up to your waist or an abdominal binder - basically a big elastic girdle like belt that squeeze your whole mid-section. Ladies - you don't need an abdominal binder from a medical supply store, you can just wear those tummy control "Spanx" or a corset like undergarment that holds in your tummy and love handles.
Large meals also make me POTS triggered acid reflux/GERD worse, so there's another reason I avoid large meals.
Avoid High Carb Meals/Sugary Meals
Some patients also have reactive hypoglycemia. Whether this is directly related to POTS or a separate medical problem that some POTS patients just happen to have, is not clear.
Reactive Hypoglycemia is not the same thing as hypoglycemia caused by diabetes. It is a temporary state of hypoglycemic symptoms like shakiness, cold, shivering, heart palpitations, etc. occurring 1-2 hours after eating a high carb or sugary meal. It is thought to be be caused by an inappropriately high insulin release into the body in response to the high carb/sugary meal. They only real treatment for it is to not eat high carb sugary meals - which is healthier for you anyways.
If you are having these hypoglycemic symptoms at all, it is a good idea to been seen by a doctor to make sure your don't have diabetes, which is a very serious disease.
Avoid Junk Food
If you have POTS, you need nutrition packed healthy food, not junk food. You probably need more than the normal potassium, magnesium and calcium. You can cheat and take a multi-vitamin, but you're body will be able to absorb those important vitamins and minerals better from food, rather than synthetic chemicals packed into a little capsule. Most people think if you take Vitamin C (ascorbic acid) in a pill, you're getting the amount of Vitamin C in your body as it claims on the label. Did you know that your body needs other substances in order to be able to absorb and utilize the ascorbic acid. Guess where these other substances are found - in citrus fruits and other food sources of ascorbic acid. If you have really good vitamins, they may contain some of these compltementary substance, like bioflavanoids, but mother nature is not easy to bottle, so you are better off getting your nutritional needs met by eating healthy food, the way mother nature intended.
Also, junk food has so many nasty chemicals, like petroleum by-prodcts (most food coloring and artificial flavorings). If you're not feeling well, your body is telling you that it is under a great deal of stress. When you eat junk food, you are just adding stress to your body. To think about this another way... you wouldn't eat coal tar, so why would you eat something that is made from it? If you can't pronounce it, don't eat it.
Becoming dehydrated causes low blood volume (hypovolemia), low blood pressure (hypotension) and puts unneeded stress on all of your organs. Some POTSies are more prone to dehydration in the first place, so it takes extra effort to say properly hydrated and keep the devastating symptoms caused by hypovolemia and hypotension at bay.
Avoid Hot Baths/Hot Tubs/Pools/Saunas/Steam Rooms/Hot Weather
Submersing yourself in hot water or hanging out in hot sauna dilates the blood vessels in your skin, which lowers your blood pressure. This can increase your POTS symptoms, and some POTSies take a longer time to recover from dilated blood vessels that healthy people, because their autonomic nervous system doesn't respond properly. S if you have POTS, you may want to skip the "hot yoga" class. Regular swimming pools can even be hot enough to trigger this if you are sensitive. Heated indoor swimming pools are kept anywhere from 92-100 degrees, and the air will be steamy warm in an indoor pool facility too, so take extra precautions.
Avoid Allergic Reactions
A naturally occurring chemical in your body called Histamine is released by your body when you have an allergic reaction to something. Besides the stuffy nose, itchy skin, watery eyes and asthma that a flurry of histamines rushing through your body can can cause, histamines also cause your blood vessels to dilate, which can lower your blood pressure. Since many POTSies already have low blood pressure, or have autonomic nerve damage that prevents their body from responding properly to changes in blood pressure, you want to avoid histamines and thus, avoid allergens.
I avoid known allergens as much as possible, use a HEPA air-filter in my house to clear the area of pollen and pet dander (I refuse to get rid of my doggie even though I'm super allergic to her) and I take over-the-counter anti-histamine medicine when my allergies get really bad (10 mg of Certirizine - generic name for Zyrtec, but much cheaper at BJs wholesale). Before POTS, I used to just grin and bear it with my allergies because they weren't so bad, but now I notice that my allergies are worse and my blood pressure and pre-syncope symptoms are noticeably worse when I'm having allergies.
Elevated histamine levels triggered by allergic reactions can also cause an increase stomach acid production, which can worsen acid reflux/GERD. In fact, many of the drugs developed to combat acid reflux are actually anti-histamine drugs (like Ranitadine), although the work on a different histmaine receptor than most drugs meant specifically for allergies. Histamine based allergy drugs target the H2 receptors associated with the lining of the stomach and histamine based acid prevention drugs target H1 receptors associated with tissue containing capillaries.
Avoid Prolonged Standing or Sitting
I'm not saying lay in bed all day (that's on the "avoid" list too), but if you stand still with your knees locked in one place for too long, eventually even the healthiest person will pass out. Gravity pulls blood down to your feet when you stand up, and moving your muscles in your lower half will help your body pump the blood back up to your heart. If you feel particularly lightheaded, there are special "counter maneuvers" you can perform to help. If you're waiting in line at the grocery store, just keep your legs moving by casually walking in place or shifting weight from one foot to the other. You can squeeze your calf, thigh or butt muscles a bit. Go up on your toes and then back to flat feet. Crossing your legs when sitting or standing, squatting, and bending at the waist can also help.
Avoid Prolonged Bed Rest
As best as you can, try not to lay like a lump in bed all day because you will get weaker, lose muscle tone, and get aching muscles and joints. Prolonged bed rest causes deconditioning, which can lead to decreased cardiac function, decreased lung function, lower blood volume, lower blood pressure, loss of bone and muscles mass, bed sores, increased likelihood of infections, etc.
If you are having a lay in bed kind of day, at least stretch and change your posture often. Try your best to walk around the bedroom a few times a day. I force myself to get out of bed during commercials when I can. Small steps are better than no steps at all, and will hopefully lead to better health in the long run.