Prescription drugs heal us when we’re sick, ease our pain when we ache, and prevent or control long-term conditions. But sometimes, even when they do the job they’re supposed to, they have unwelcome side effects.

Don’t let that make you automatically rule out a medication, especially if it’s an important part of managing a health condition. But you shouldn’t accept unpleasant reactions without question, either.

Side effects can happen with almost any medicine, says Jim Owen, doctor of pharmacy and vice president of practice and science affairs at the American Pharmacists Association. They’re common with everything from birth control pills to cancer-fighting chemotherapy drugs.

Many prescription drugs, for example, cause stomach problems like nausea, diarrhea, or constipation because they pass through your digestive system.

Others — like antidepressants, muscle relaxants, or blood pressure or diabetes meds — may cause dizziness. Some might make you feel drowsy, depressed, or irritable. Some may cause weight gain. Some may disrupt your sleep or your ability (or desire) for sex.

“I tell my patients that chronic symptoms are not acceptable,” says Lisa Liu, MD, a family doctor at Gottleib Memorial Hospital in Melrose Park, IL. “I won’t allow them to have ongoing pain or discomfort unless we have tried every alternative.”

When your doctor prescribes a new medicine, ask about common side effects.

“You, your doctor, and your pharmacist should be working together so everyone has the same information,” Owen says. “You should know which side effects are serious, which ones will go away on their own, and which ones can be prevented.”

Once you start taking a drug, mention any unexpected symptoms to your doctor or pharmacist as soon as possible. This includes changes in your sex life, Liu says, which many patients are embarrassed or afraid to talk about.

Some side effects go away over time as your body gets used to a new drug, so your doctor may recommend you stick with your current plan for a little longer. In other cases, you may be able to lower your dose, try a different drug, or add another one, like an anti-nausea medicine, to your routine.

“People often think that just because they have a bad reaction to one drug, they can’t take any other drugs in the same class, but that’s not always the case,” Liu says. “Sometimes side effects are due to very specific ingredients that not every brand uses.”

Changing the time of day you take your medicine may help, too, if your doctor gives you the OK. “If someone is on four blood pressure medications, for example, I tell them not to take them all at once,” Liu says. “For patients whose birth control or antidepressant makes them dizzy, I have them take it right before bed.”

When you talk to your doctor, have a list of all other medications or supplements you’re taking — both prescription and over-the-counter. Sometimes, side effects are caused by two or more drugs reacting negatively together, Owen says, and you may not need both.

Keep in mind that a new symptom may actually be a drug side effect. If you don’t give your doctor the whole story, they may diagnose you with another condition entirely — and prescribe another drug to treat it.

“There are a lot of factors that go into side effects — not just the medication itself,” Owen says. “You may be able to prevent them by avoiding alcohol or certain foods, or by making other small changes to your diet or lifestyle.”

For example, if you take an antidepressant that helps you feel better but also causes you to gain weight, you may have to pay more attention to your nutrition and exercise plan.

Some medicines, like cholesterol drugs and blood thinners, may not work as well if you eat grapefruit or foods high in Vitamin K. Other drugs may make you sensitive to the sun, so wear sunscreen or cover up outside.

It’s smart to do your own research about your medicine. Read the label and all the instructions that come with your prescription. Talk with other people who have similar health concerns. And search reliable sources on the Internet.

If you read or hear about another drug that may have fewer side effects, ask your doctor or pharmacist about it. Side effects of newer medications may not be as well-known as those on the market for years, so you might ask about switching to an older, more proven drug.

But never stop a medicine or change your dosage without your doctor’s approval — especially if you’re being treated for a serious health condition. You need to take some medicines, like antibiotics, for a full course to avoid getting sick again. Others don’t work as well if you skip a dose, cut it in half, or take it with or without food.

You may be able to tolerate some side effects, especially if they’re temporary or if the pros outweigh the cons. But if a bad drug reaction puts you at risk for more medical problems or seriously affects your health, it may be time for a change.

Medications that cause dizziness, for example, can increase your risk of death or serious injury from falling — especially if you’re an older adult. And treatments that affect your ability to enjoy time with friends or romantic partners may not be your best option if alternatives are available.

“Sometimes it takes a bit of trial and error,” Liu says, “but a lot of times you can find a medicine that works without affecting your quality of life.”