What Is the P10 Pill? Identification, Uses, and Safety

A pill stamped “P10” is most commonly a 10-milligram tablet of prednisone, a widely prescribed corticosteroid used to treat inflammation and immune-related conditions. However, similar imprints can appear on other medications, including buspirone hydrochloride 10 mg, an anti-anxiety drug with an entirely different purpose and risk profile. Because a single imprint code does not guarantee a single drug, confirming exactly what you have matters before you swallow anything or hand it to someone else.

How to Confirm What Your P10 Pill Contains

Pill imprints in the United States are required by the FDA so that every solid oral medication can be traced back to its manufacturer and active ingredient. But the system is not as foolproof as it sounds. Different manufacturers can use overlapping letter-number combinations, so “P10” alone does not lock in a single product. To narrow things down, you need to note four characteristics beyond the imprint: the pill’s color, shape, any score line (that shallow groove for splitting a tablet in half), and the presence of any additional markings on the reverse side. A white, round tablet stamped “P10” with a score line on the back is the profile most commonly matched to prednisone 10 mg in major US drug databases. If the shape is oblong or the color differs, you may be looking at a different medication entirely.

Your pharmacist is the fastest and most reliable resource. They can scan or look up the imprint in seconds and confirm what the pill is. If you cannot reach a pharmacist, the FDA’s online pill identifier and the National Library of Medicine’s DailyMed database both allow searches by imprint, color, and shape. Poison control centers also handle these requests routinely. In fact, pill identification now accounts for roughly a quarter of all calls to US poison centers, and the volume of these requests from the public rose by over 100 percent over a six-year study period.

Prednisone 10 mg as the Most Common Match

Prednisone is a synthetic glucocorticoid, a class of steroid hormones that your adrenal glands produce naturally in smaller amounts. In its 10 mg tablet form, it is one of the most frequently prescribed strengths, used across dozens of conditions where the immune system or inflammatory response needs to be dialed back. It is available as a generic from many manufacturers, which is part of why the P10 imprint shows up so often. Doctors prescribe it for conditions ranging from rheumatoid arthritis and asthma flares to allergic reactions, inflammatory bowel disease, and certain skin conditions. It is also used short-term at higher doses for acute episodes like severe poison ivy or gout attacks, and at lower doses for longer-term management of autoimmune diseases.

In rheumatoid arthritis, for example, adding 10 mg of daily prednisone to a standard treatment regimen has been shown to slow joint damage on X-rays and reduce the need for more aggressive biologic drugs, without increasing steroid-related complications over the follow-up period.¹ That finding is specific to early RA treated alongside methotrexate, but it illustrates why 10 mg is such a common dose: it is high enough to meaningfully suppress inflammation yet low enough that many patients tolerate it reasonably well.

How Prednisone Works in the Body

Once you swallow prednisone, your liver converts it into its active form, prednisolone. From there, the drug enters cells and binds to glucocorticoid receptors floating in the cytoplasm. These receptors then pair up and travel into the cell’s nucleus, where they latch onto specific stretches of DNA and either ramp up or shut down the production of certain proteins.² Among the proteins it boosts are natural anti-inflammatory molecules. At the same time, prednisone suppresses the production of chemicals that drive inflammation, including prostaglandins and cytokines. The net effect is a broad dampening of the immune response, which is why a single drug can treat such a wide range of conditions and also why it can cause trouble if used carelessly.

This broad mechanism is both prednisone’s strength and its weakness. Because it does not target one specific pathway, it reduces inflammation effectively across many tissue types. But that same lack of precision means it affects systems you would rather leave alone, from bone density to blood sugar regulation to your body’s ability to fight infections.

Why You Cannot Just Stop Taking Prednisone

If you have been taking prednisone for more than about three to four weeks, stopping abruptly can be genuinely dangerous. The reason is that your adrenal glands, which normally produce cortisol on their own, start to go dormant when an external source of glucocorticoid floods the system. This is called hypothalamic-pituitary-adrenal axis suppression. The glands essentially get the signal that there is plenty of cortisol already and stop making their own.³ If you then suddenly remove the external supply by quitting the drug, your body is left with almost no cortisol at all. The result can range from fatigue, muscle aches, and nausea to a full-blown adrenal crisis with dangerously low blood pressure.

This is why doctors taper the dose, gradually reducing it over days or weeks to give the adrenal glands time to wake back up and resume cortisol production. The taper schedule depends on how long you have been on the drug, how high the dose was, and whether the underlying condition is likely to flare when the steroid is withdrawn.⁴ Short courses of a few days, like a five-day “burst” for an asthma flare, usually do not require tapering. But anything beyond a few weeks almost always does. If you find an unidentified P10 pill and suspect someone in your household may have stopped taking prednisone without tapering, that is worth a call to their doctor.

Common Side Effects of Prednisone at 10 mg

At 10 mg per day, prednisone’s side effects depend heavily on how long you take it. A short course of a week or two might cause increased appetite, mild mood changes, difficulty sleeping, or a slight rise in blood sugar. These effects are annoying but generally resolve once the drug is stopped.

Longer-term use is where the risk profile shifts. Over months to years, prednisone at even moderate doses can contribute to:

Weight gain: particularly around the face and midsection, sometimes called a “moon face” or “buffalo hump” distribution.
Bone thinning: glucocorticoids interfere with bone formation, and osteoporosis is one of the most common long-term consequences.
Blood sugar elevation: prednisone can push people with borderline glucose control into diabetic ranges, and it worsens control in those who already have diabetes.
Skin changes: easy bruising, thinning skin, and slower wound healing.
Immune suppression: increased vulnerability to infections, sometimes including unusual ones that healthy immune systems normally keep in check.
Mood and sleep disturbances: ranging from restlessness and insomnia to irritability or, in some cases, more significant psychiatric effects at higher doses.

Not everyone on 10 mg daily will experience all of these, and many people tolerate the dose well for extended periods, especially when their doctor monitors them with periodic blood work and bone density screening. The risk is cumulative, though, so the goal is usually to find the lowest effective dose and step down whenever the underlying disease allows.

When P10 Might Be Buspirone Instead

Some manufacturers stamp “P10” or very similar imprints on buspirone hydrochloride 10 mg tablets. Buspirone is an entirely different class of medication, an anxiolytic prescribed for generalized anxiety disorder. It works on serotonin receptors in the brain rather than on the immune system, and its side effect profile bears no resemblance to prednisone’s. The two pills sometimes share a white, round appearance, which makes visual identification tricky without checking additional markings on the tablet’s reverse side or confirming with a pharmacist.

Buspirone is generally considered to have a milder side effect profile than many other anti-anxiety drugs, but it is not without risks. A large pharmacovigilance analysis of real-world adverse event reports found that the most frequently reported problems were dizziness, anxiety (paradoxically), drug interactions, serotonin syndrome, and tremor.⁵ The serotonin syndrome risk is particularly worth knowing about. When buspirone is taken alongside certain antidepressants, especially SSRIs like fluoxetine, the combined effect on serotonin can tip the system into a dangerous overstimulation marked by agitation, rapid heart rate, high body temperature, and muscle rigidity.⁶ This is a medical emergency, and anyone combining buspirone with other serotonin-affecting drugs should be aware of the warning signs.

The practical lesson here is straightforward: if you find a pill marked “P10” and are trying to figure out what it is, do not assume it is one drug or the other based on the imprint alone. Taking even one dose of the wrong medication can range from ineffective to harmful, especially if the person has allergies or takes other drugs that interact badly with one of the two possibilities.

The Counterfeit Pill Problem

While prednisone and buspirone are not among the most counterfeited drugs, anyone trying to identify an unknown pill should understand the broader landscape. Illicit pill pressing has exploded in recent years, and counterfeit tablets often look convincingly like legitimate pharmaceuticals. Over a quarter of fentanyl seizures in the United States are now in pill form, with counterfeit versions disguised as oxycodone, alprazolam, and other controlled substances.⁷ An ethnographic study of tourist-oriented pharmacies in Mexico found that 40 percent of samples sold as controlled substances were counterfeit, with pills marketed as Adderall actually containing methamphetamine and pills sold as oxycodone containing fentanyl or heroin.⁸

Prednisone and buspirone are not high-value targets for counterfeiters because neither has significant street value. Counterfeit operations focus on opioids, benzodiazepines, and stimulants. Still, if you acquired a pill outside a licensed US pharmacy, visual identification alone is not enough to guarantee what is inside. Fentanyl test strips can detect fentanyl contamination but will not tell you what the pill actually is. When in doubt, take the pill to a pharmacist or call poison control rather than trying to figure it out by matching photos online.

How Reliable Are Online and App-Based Pill Identifiers?

Dozens of websites and smartphone apps let you type in an imprint code, select a color and shape, and receive a list of possible matches. The FDA’s own tool and DailyMed are the most authoritative of these, drawing directly from the agency’s National Drug Code database. They work well when the imprint is clear and you accurately describe the other features. Where things get less reliable is with worn or partially illegible tablets, where the “P” might look like a “D” or the “10” could be “16.”

Researchers have been developing deep-learning systems that identify pills from photographs, which could eventually help people who cannot read the imprint clearly. One such system achieved about 75 percent accuracy on its first guess when tested against US pill images it had never been trained on, and nearly 80 percent accuracy when evaluated with real consumer-taken photos.⁹ A separate deep-learning approach using a different architecture reached above 95 percent accuracy for its top match and over 99 percent when looking at its top ten suggestions.¹⁰ These numbers sound impressive, but in practice they mean the algorithm still gets it wrong a meaningful percentage of the time, especially with real-world photos taken under uneven lighting or against busy backgrounds. These tools are useful as a first step but should not replace confirmation from a pharmacist.

What to Do with Leftover or Unidentified Pills

If you have identified your P10 pill and no longer need it, or if you have leftover medication from a completed course, proper disposal matters. Prednisone left in a medicine cabinet is a risk for accidental ingestion by children or pets, and buspirone, though not a controlled substance, should also be kept out of reach. The safest route is a DEA-authorized drug take-back program, often hosted at local pharmacies or law enforcement offices. If no take-back option is convenient, single-use home disposal systems allow you to deactivate unused medication and throw it away without flushing it, which avoids introducing pharmaceuticals into the water supply.¹¹

For prednisone specifically, keep in mind that if you are disposing of leftover pills because you feel better and want to stop early, that decision should involve your doctor. As covered earlier, abruptly stopping after more than a few weeks of use risks adrenal insufficiency. “I feel fine so I’ll stop” is exactly the scenario where people run into trouble, because the symptoms of adrenal insufficiency can take a day or two to appear and then escalate quickly.

When a Pill Found Loose Deserves Extra Caution

People find unmarked or partially identified pills in all kinds of places: a coat pocket from last winter, a plastic bag in a teenager’s room, the bottom of a purse, a communal workplace drawer. The instinct is often to try to figure out what it is and either take it yourself or throw it away. Neither response is ideal without knowing what you are dealing with. A 10 mg prednisone tablet accidentally taken by someone on blood thinners, for instance, could worsen their bleeding risk. A buspirone tablet taken by someone already on an SSRI could increase the chance of serotonin-related side effects.

If you find an unknown pill and suspect it belongs to someone in your household, ask them first. If the pill is truly a mystery, a pharmacist can identify it quickly, and you can then make an informed decision about disposal. Poison control centers, reachable at 1-800-222-1222 in the US, exist specifically for this kind of uncertainty and will walk you through what to do whether someone has already taken the pill or you just want to know what it is.