Okay, let's tackle this question about the side effects of tacrolimus. The question is asking which of the options is NOT a side effect. First, I need to recall what tacrolimus does and its common adverse effects.

Tacrolimus is an immunosuppressant used in transplant patients. Its main mechanism is inhibiting calcineurin, which prevents the activation of T-cells by blocking the production of IL-2. Common side effects include nephrotoxicity, hypertension, hyperkalemia, and tremors. It can also cause neurotoxicity like headaches or seizures.

Now, looking at the options (even though the actual options aren't provided), the correct answer would be the one that's not typically associated. For example, if one of the options is hypoglycemia, that's a red herring because tacrolimus is known to cause hyperglycemia, not the opposite. Another possible incorrect side effect might be anemia, but tacrolimus doesn't typically cause anemia. Wait, actually, some side effects include anemia, so maybe that's a distractor. Hmm, need to be careful here.

Let me think of common side effects again. Nephrotoxicity is a big one. Hyperkalemia because it inhibits aldosterone action. Neurotoxicity. Hypertension. Hyperglycemia. So if the options include something like hypokalemia, that's incorrect because it's hyperkalemia. Or if it's a gastrointestinal issue like diarrhea, but tacrolimus can cause GI symptoms like nausea, but not sure about diarrhea. Maybe the wrong option is something like ototoxicity, which is more with aminoglycosides or certain diuretics, not tacrolimus.

The key here is to identify the least common or non-existent side effect among the options. Let's structure the explanation: core concept is that tacrolimus is a calcineurin inhibitor with specific side effects. The correct answer would be the one not in that list. For example, if the options are A: Nephrotoxicity, B: Hyperkalemia, C: Hypertension, D: Hypoglycemia. Then D is the correct answer because hyperglycemia is typical, not hypoglycemia.

So the explanation would mention the core mechanism, explain why the correct answer isn't a side effect, and then address each wrong option. The clinical pearl would be to remember the key side effects like nephrotoxicity, hyperkalemia, hypertension, and neurotoxicity.

**Core Concept**
Tacrolimus is a calcineurin inhibitor used in immunosuppression post-transplant. Its side effects stem from inhibition of calcineurin in T-cells and other tissues, leading to vasoconstriction, electrolyte imbalances, and neurotoxicity. Classic adverse effects include nephrotoxicity, hypertension, hyperkalemia, and tremors.

**Why the Correct Answer is Right**
The correct answer is the option that does **not** align with tacrolimus’ known side effects. For example, if the correct answer is **hypoglycemia**, this is incorrect because tacrolimus typically causes **hyperglycemia** due to pancreatic beta-cell toxicity and insulin resistance. It does not stimulate insulin

✓ Correct Answer: B. Ototoxicity