The first few months after starting HIV treatment are pivotal in determining whether your first regimen will be successful. Yet, if you are brand new to HIV treatment, how can you know what success is? It can be hard to tell the difference between a warning sign that your regimen might not be right for you and a normal signal that your body is still adjusting to the medications.

First and foremost, it's important to know that if your HIV medications (called antiretrovirals) are chosen appropriately (accounting for baseline drug resistance and underlying health issues such as liver, kidney or heart risks), and if you're able to be adherent to those medications (the goal is taking more than 90% of your pills), then HIV treatment works. Side effects with today's medications are uncommon and usually mild. Treatment failure and HIV drug resistance, once common, are now exceptionally rare in people who take their medications. Your health can be protected from developing AIDS, serious infections and cancers; and with an undetectable HIV viral load, you won't transmit the virus to others.

No one wants to take medications that could make him or her feel worse than before. It also seems pointless to take a medication every day that isn't working right. It helps to pay close attention, communicate with your health care team and be a part of every decision.

How do you really know if your HIV treatment is working? There are three key things to keep track of: how much your viral load is dropping, how much your immune system is recovering and how you're actually feeling.

Is My Viral Load Dropping Enough?

The Basics

The goal of HIV treatment is to disrupt the replication of the virus so much that the amount circulating in your blood is as low as possible -- so low that the blood tests you'll use to keep track of your HIV will report it as "undetectable." No matter how high your viral load is when you start treatment, "undetectable" is where you want to go.

How long it takes to reach an undetectable viral load is very much influenced by how high your viral load is at the start. Treatments that include a HIV integrase inhibitor cause more rapid declines in viral load than other families of medicines. While more virus for HIV medications to attack often means more time to reach an undetectable level, if you're adherent to your meds, your viral load should be undetectable within six months of starting treatment, and often much sooner.

It's unlikely your health care provider will even start checking your viral load until you've been on your medications for at least a few weeks. According to U.S. treatment guidelines, viral load should be checked around two to eight weeks after starting treatment and every three to six months thereafter. Although checking earlier may give you a sense of the pace of the viral load drop, it's getting to undetectable that really matters, and that can take time. For adherent patients with consistently suppressed viral loads and normal CD4 counts for more than two years, viral load monitoring can be done at six-month intervals.

Different Definitions of "Undetectable"

What makes conversations about viral load testing even more confusing is that "undetectable" doesn't always mean the same thing. Different clinics use different tests analyzed by different laboratories, and each lab may have a different cut-off point for measuring HIV in a sample of blood. So, if your lab test has 50 copies/mL as the lowest detectable amount, but your friend's lab test detects viral loads as low as 20 copies/mL, what does it mean if your friend has detectable virus and you do not?

Obviously, less is better when it comes to HIV viral load. But we don't know precisely the significance of, let's say, 50 copies/mL versus 20 copies/mL. Measuring such tiny amounts of HIV in the blood is still a tricky business, and there is even some question about how reliable the measures are: If you were to repeat a viral load test, even with the same sample of blood in the same lab, the result would not necessarily be exactly the same.

The Mystery of "Blips"

Even if you achieve an undetectable viral load (called "fully suppressed") and stay undetectable, it is possible that you will experience a small rebound to a viral load that's detectable but still very low (i.e., below 400 copies/mL). This is called a viral load "blip."

There can be a variety of reasons for a blip (including lab variability or error), not all of which we completely understand. However, it does not mean the regimen has failed. Repeat testing will tell the story; if future tests show a three-fold increase or more in the amount of virus, then you and your provider may want to talk about your adherence to meds, additional monitoring tests (such as viral drug resistance tests) and, perhaps, switching to a different regimen.

The Bottom Line

Let's say you've been on your medications for several months, and what had been a consistent decline in your viral load has leveled out without reaching an undetectable level -- or, worse, your viral load is going back up. If this happens, you and your provider will want to figure out and address what might be slowing your treatment progress and decide whether you need to switch regimens. The longer you stay on a combination that isn't fully suppressing the virus, the more risk there is of the virus becoming resistant to those medications, as well as other HIV medications you haven't even taken yet (called cross-resistance).

But when you're just starting out, as long as your viral load is generally moving toward undetectable, you're in good shape.

Is My Immune System Recovering Enough?

The Basics

Remember that HIV infects and kills an important part of our immune system called CD4 cells. As we just discussed, an effective antiretroviral regimen should prevent replication of HIV and immune injury. That gives your immune system a break from HIV and allows it to stay healthy (if your CD4 levels are normal) or recover (if your CD4 levels have already been lowered). When it comes to measuring immune recovery, the conversation revolves around two major laboratory markers: your "absolute CD4 cell count" and your "CD4 percentage," or the proportion of your white blood cells that are CD4 cells.

Depending on the person, the pace of a rise in CD4 cells can be amazingly fast, frustratingly slow or somewhere in between. People who begin treatment at a low CD4 cell count (below 200) often have a steeper hill to climb, and depending on how weak their immune system is to begin with, it may take longer to climb it. Other people might see a rise and then a leveling out, then see another rise after a long time on treatment.

The main measure of your health, of course, is whether you get sick any more often (or with more severity) than an HIV-negative person. But, we can use CD4 count and CD4 percentage as ways to gauge the likelihood that you'll develop illnesses in the future.

A Tricky Measuring Tool

The problem with obsessing about your CD4 cell count is that it can mislead you. Getting over a cold? Stressed out? Recently vaccinated? Getting your blood drawn at a different time of day than usual? Any of these things and more can influence the number you'll get back from the lab.

Your CD4 percentage is less variable than your CD4 count because, if your absolute number of CD4 cells/mL is down, it's sometimes because the larger pool of white blood cells is also down. CD4 numbers can fluctuate a lot, even in healthy people. A significant change in CD4 is considered a 30% change in absolute count or three percentage points. This is why knowing the percentage of white blood cells that are CD4 cells can be more useful: It can help distinguish a real change from one that looks like a big deal but isn't.

Another thing that can complicate setting a specific CD4 number as a goal for HIV treatment is that everybody is different. A "normal" CD4 count for an HIV-negative person can be anywhere between 500 and 1500, and a "normal" CD4 percentage can vary from 30% to 60%.

While it is understandable why people worry about their "numbers," if your viral load is suppressed and CD4 values have been normal for more than two years, as long as you stay adherent to treatment, you no longer need to worry about the numbers. Current U.S. treatment guidelines tell us that monitoring the CD4 state is no longer important because your immune system is normal.

The Bottom Line

HIV treatments work to allow your immune system to recover. You likely don't know what your normal count was long before you acquired HIV, and everyone is different, but in general more CD4 cells (and a higher CD4 percentage) are a good thing. Talk to your health care provider about what your test results mean. If you've maintained viral suppression and your CD4 numbers are in the normal range, you can take a deep breath and relax -- you might even not need to worry about CD4s in the future. If your counts remain low, be patient because some people do take longer to recover than others.

How Am I Feeling?

The Basics

There are few certainties in HIV treatment, but one is that you can't tell what your viral load or CD4 count is by how you feel. Only those blood tests you take can tell you for sure. However, how you feel can tell you a lot about a lot.

Every medication in the world has potential side effects and toxicities. Some meds are more likely to cause side effects than others, and some may be more likely in some people than others. It's important to take note of changes in the way you feel after you start treatment and beyond -- both physically and mentally.

In the Beginning

With today's medications, most people don't notice much of anything when they start treatment. Others have a minor side effect or two that will dissipate over the first few weeks. Still others have severe side effects that can make daily life harder; they may go away after a few weeks, or (rarely) they may persist.

If you get a new symptom after starting treatment that becomes worse or doesn't go away, it's important to bring it to your doctor's attention. There might be blood tests to run to see how your liver or kidneys are doing with the medications, and the two of you can hatch a plan forward. If the symptoms are related to one of your medications, switching to a different medication should alleviate the side effect and any health risks.

Look Into the IRIS

People who start treatment at low CD4 cell counts (particularly when it's below 200) might suddenly experience a whole array of symptoms: fever, swollen lymph nodes, congested breathing and other symptoms that you might feel if your body were reacting to a bacterial or viral infection.

In fact, that's likely exactly what's happening: What you're experiencing may well be Immune Reconstitution Inflammatory Syndrome (IRIS). IRIS is a sign that the medications you're taking are helping the immune system, and as a result, your body is now able to recognize and mount a response to invaders that have been taking advantage of your weakened state. Although IRIS might make you feel worse at first, once your recovering immune system fights off the infection, you'll start to feel much, much better than before you started treatment.

However, if you develop symptoms of IRIS, it also means your doctor should be involved, and usually, it means continuing on your HIV medications. This is because extreme cases of IRIS can cause you to get very sick and sometimes require hospitalization, which will let your doctor provide close monitoring and support until you recover.

Watching the Horizon

After a while on treatment, you might find that you're experiencing a side effect you didn't notice before or that bothers you now more than it used to. For instance, maybe you started meds and discovered over the course of several months that your sleep isn't that great or your mood has slipped.

While today's medications are vastly better tolerated than those in the past, there are still unanswered questions about the long-term effects of HIV medications. We know that they can allow essentially normal life expectancy and excellent quality of life. But, be sure to stay in touch with your doctor about some of these potential long-term health issues, and use TheBody.com as a resource to stay educated about side effects and other problems that people with HIV may get as they grow older.

The Bottom Line

If you find yourself not feeling well days, weeks or months after you've started HIV treatment -- particularly if that feeling isn't going away or is getting worse -- the question quickly becomes: "Do I want to try to find ways to manage this symptom because my regimen is working and I'm able to keep up with my meds every day? Or, do I want to see what a new regimen has to offer, both good and bad?" This is an individual decision, one best made thoughtfully and carefully after discussion with your health care provider.

It can be nerve-wracking to start an antiretroviral regimen. Fortunately, the fear of what might happen is usually worse than what actually happens. In fact, the vast majority of people feel better after they start HIV treatment: They feel better physically because the medications are stopping the unchecked replication of HIV in their bodies and helping their immune systems to recover. And they feel better emotionally because, well, they feel better physically -- and because many of the fears they had about HIV treatment weren't realized.

Still, the key for anybody beginning treatment is to be aware of these potential warning signs, educate yourself about their causes and solutions, and talk openly with your health care provider about concerns and options. Doing so will help ensure that your treatment remains on track no matter what obstacles pop up.

Myles Helfand is the editorial director of TheBody.com and TheBodyPRO.com.

Follow Myles on Twitter: @MylesatTheBody.