Factors Determining If One Will Get Side-Effects From Drugs (Why do Some People Get Side-Effects to Medications and Others Get None At All?)

This is another Area'1255 : "Questions & Answers" Chapter.

† Q †

Why do some People get side-effects from Medications & Others do Not?

† A †

Multiple factors play a role in drug side-effects. 

1. Because drugs often act upon certain proteins, enzymes, or receptors in the body, and attach often, quicker than natural molecules, and exert actions at higher rates in comparison to natural molecules, the 'side-effects' are simply 'direct actions' and manifestations of the potency of the drug. However, it occurs because of rapid physiological changes by the body , by the means of actions on the molecular targets of the drug. Some people who get more severe side-effects, are people who were at a lower setpoint and likely had severe deficiency in whatever chemical the drug is acting on, or an excess at whatever the drug is reducing/blocking.
2. General Health plays a large factor, for example, one is less likely to develop immune deficiencies to certain drugs if they are already very healthy. So medications that reduce white blood cells are often a result of their interactions with enzymes that may already be partially, or significantly impacted based on the current health of that individual. 
3. Histamine levels play a role in drug side-effects (!) , those with lower histamine levels may experience less side-effects to certain medications in general [see here]. Whereas high histamine levels may be potentially protective against drug side-effects in some circumstances, particularly regarding bradycardic drugs, histamine may protect against low heart rate induced by drugs <Reference>. Dietary changes aimed at reducing histamine levels and other inflammatory chemicals will not set in place immediately, so a lessening of drug side-effects should not be expected if one is only 1-6 months in to their ''healthy diet''. Rather, it is to be expected that if one eats very healthy, including tons of fruits, vegetables, and in general gets a great amount of nutrients, that 12 months in + will impact the responses to any insult or change within an organ or system of cell communications which a drug may impact.
4. People with low histamine will be particularly vulnerable to stimulants and medications that increase blood pressure | ! |. People with high histamine are vulnerable to any medication or substance that lowers blood pressure  [R1] | [R2]. Increased histamine levels may be beneficial and even crucial for those people taking SSRI's for Depression |!|. Histamines are necessary for those anti-depressants to work properly.
5. Levels of Sex-Hormones impact heart related side-effects of certain drugs, for example, Men with high levels of dihydrotestosterone and decent fitness level will likely NOT develop a 'long-QT-syndrome' from psychiatric and other QT-prolonging medications.+See Article Here/