Treating high calcium depends on how elevated your levels are and what’s causing them. Mild cases often resolve by addressing the underlying cause, such as switching a medication or treating an overactive parathyroid gland. Calcium levels above 12 mg/dL are considered critical, and levels above 15 mg/dL require emergency treatment. Most people with high calcium need a combination of rehydration, medication adjustments, and sometimes hospital-based therapies to bring levels back to normal.
What Counts as High Calcium
Normal blood calcium falls between roughly 8.5 and 10.5 mg/dL. Levels above 10.5 mg/dL are technically elevated, but many people don’t feel symptoms until calcium climbs past 11.5 mg/dL. Some people remain symptom-free even at that level, which is why high calcium is sometimes caught on routine bloodwork before you notice anything wrong.
Once calcium crosses 12 mg/dL, the risk of serious complications rises sharply. Above 15 mg/dL is a medical emergency that can cause dangerous heart rhythm changes, confusion, and kidney damage. Where your level falls on this spectrum determines how aggressively it needs to be treated.
Hydration as the First Step
Dehydration makes high calcium worse because your kidneys need adequate fluid to flush excess calcium into your urine. If you’re mildly elevated and otherwise healthy, increasing your daily water intake may be enough to nudge levels down on its own. Your doctor can recommend a specific daily volume based on your kidney function and heart health.
For moderate to severe cases treated in a hospital, intravenous saline is the standard first move. Current guidelines call for 4 to 6 liters of normal saline over 24 hours in dehydrated patients. People with kidney problems, heart failure risk, or older adults typically receive a lower volume (1 to 3 liters) to avoid fluid overload. This aggressive hydration dilutes calcium in the blood and helps the kidneys excrete it faster. In many cases, rehydration alone brings calcium down enough that additional treatment isn’t needed.
Medications That Lower Calcium
When hydration alone isn’t enough, hospital-based medications target calcium through different mechanisms and timelines.
Fast-Acting Options
Calcitonin is a hormone-based injection that works within hours, making it the go-to for buying time while slower treatments kick in. It’s given as an injection every 12 hours, with the dose based on body weight. The catch is that calcitonin loses effectiveness after about 48 hours as your body adapts to it. It’s rarely used as a standalone treatment for that reason, but it’s valuable for getting dangerously high levels down quickly.
Longer-Lasting Options
Bisphosphonates are the workhorse medications for bringing calcium down and keeping it there. These drugs block the cells that break down bone, which is where excess calcium often enters the bloodstream. Two are commonly used: one given as a 15-minute infusion and another given over 2 to 6 hours. Both take 48 to 72 hours to start working, with full effect at around 7 days. That delayed onset is why calcitonin is often used alongside them to bridge the gap.
These medications carry some long-term risks worth knowing about. They’ve been linked to jaw bone problems (particularly if you need dental surgery), unusual fractures in the thigh bone, and ear canal issues. If you’re prescribed one, keeping up with regular dental checkups and reporting any new hip, thigh, or groin pain matters. After infusion, your medical team will monitor your electrolyte levels closely because calcium, magnesium, and phosphate can all drop too low in response.
For patients whose calcium doesn’t respond to bisphosphonates, or whose kidneys are too impaired to tolerate them, an alternative injection can be given under the skin. This option works through a different mechanism and follows a specific schedule: an initial dose, with repeat doses at day 8 and day 15 if calcium remains high. Blood levels are checked every few days during this period to track the response.
Treating the Underlying Cause
Lowering calcium in the short term only solves half the problem. If the underlying cause isn’t addressed, levels will climb back up.
The most common cause of high calcium in otherwise healthy people is an overactive parathyroid gland, a condition called primary hyperparathyroidism. The parathyroid glands (four tiny glands behind your thyroid) regulate calcium, and when one develops a benign growth, it pumps out too much parathyroid hormone. Surgery to remove the overactive gland is often curative.
In people with cancer, high calcium happens because tumors can release proteins that mimic parathyroid hormone or because cancer has spread to the bones. Treating the cancer itself is the most effective long-term strategy for controlling calcium in these cases.
Medication-Related Causes
Certain common medications can push calcium levels up. Thiazide diuretics, widely prescribed for blood pressure, increase the amount of calcium your kidneys reabsorb back into the bloodstream instead of excreting it in urine. Lithium, used for bipolar disorder, can stimulate the parathyroid glands and raise calcium over time. If either of these medications is contributing to your high calcium, your doctor may switch you to an alternative. Don’t stop these medications on your own, since abrupt discontinuation can cause other problems.
Excessive vitamin D supplementation is another increasingly common culprit. Because vitamin D increases calcium absorption from food, taking high doses can tip your blood calcium over the normal range. If you’re taking vitamin D supplements and your calcium is elevated, your doctor will likely ask you to stop or significantly reduce your dose.
Dietary Changes That Help
Dietary adjustments alone won’t fix significantly elevated calcium, but they play a supporting role, especially for mild elevations or as part of ongoing management after treatment.
The primary recommendation is to reduce or temporarily eliminate high-calcium foods. That means cutting back on dairy products like cheese, milk, yogurt, and ice cream. If your doctor allows you to continue eating some dairy, avoid products with added calcium, which are common in fortified milks and yogurts. Calcium-fortified orange juice, cereals, and plant milks should also be limited.
Staying well-hydrated is equally important for long-term management. Water helps your kidneys clear calcium continuously, and even mild dehydration can cause levels to creep upward. Your doctor can give you a specific daily water target, but for most people with a history of high calcium, drinking more fluid than you think you need is a reasonable starting point.
What Recovery and Monitoring Look Like
If you’ve been hospitalized for high calcium, expect blood draws every day or two to track your response. After bisphosphonate treatment, the full effect takes about a week to appear, so you may stay in the hospital or return for follow-up labs during that window. Once calcium normalizes, the monitoring schedule depends on the cause. People with parathyroid disease who haven’t had surgery may need calcium checked every few months. Those with cancer-related high calcium often have it monitored alongside their oncology care.
For mild cases managed as an outpatient, your doctor will typically recheck calcium within a few weeks of making changes, whether that’s adjusting medications, increasing hydration, or modifying your diet. Persistent or recurrent elevations usually trigger a workup to identify the underlying cause if one hasn’t already been found.