Carbidopa / Levodopa Dosages for Adults: Your GoodRx Guide

There are various ways to treat Parkinson’s disease (PD), but the go-to treatment involves medications that increase the level of a chemical in the body called dopamine. One common example of these medications is carbidopa / levodopa (Sinemet).

Carbidopa / levodopa is a first-choice option for treating PD symptoms. It also treats parkinsonism (conditions that cause PD symptoms like slowness, stiffness, and muscle rigidity). 

It’s a combination of two medications: carbidopa and levodopa. Levodopa replaces dopamine, which improves symptoms of PD. And carbidopa helps levodopa stick around longer in the body.

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If you’ve been prescribed carbidopa / levodopa, your healthcare provider may raise your dosage over time, depending on how much your PD symptoms improve with the medication. Here, we’ll cover what you need to know about carbidopa / levodopa dosages and the different forms that are available.

Note: Carbidopa / levodopa is only FDA approved to treat adults, so you won’t find children’s dosages in this guide.

What’s the typical carbidopa / levodopa dosage for adults?

The best carbidopa / levodopa dosage for you depends on how severe your PD symptoms are, and what carbidopa / levodopa product you’re taking. This medication comes in a variety of forms, including:

• Immediate-release (IR) tablets, including Sinemet, Dhivy, Lodosyn

• IR orally disintegrating tablets (ODTs)

• Extended-release (ER) tablets

• ER capsules, such as Rytary

• Liquid form, such as Duopa, that’s continually pumped into the intestines through a PEG-J tube

The IR tablets, ER tablets, and the ODTs are available as generics. We’ll focus on these dosage forms in this article, because they are the most commonly prescribed.

IR tablets and ODTs

For IR tablets and ODTs, the typical starting carbidopa / levodopa dosage is one 25 mg/100 mg tablet by mouth 3 times a day. Your healthcare provider may increase your dosage if your PD symptoms continue to be bothersome. The maximum dosage is eight 25 mg/100 mg tablets a day (or 200 mg of carbidopa per day).

There are also 10 mg/100 mg and 25 mg/250 mg IR tablets and ODTs. Different tablets can be combined to reach the desired total daily dosage.

ER tablets

The typical starting dosage of carbidopa / levodopa ER tablets is one 50 mg/200 mg tablet twice a day. The doses should be taken at least 6 hours apart to start. Your healthcare provider may increase your dosage every 3 days or more until you reach a dosage that’s right for you. Maintenance doses can be given as often as every 4 hours, or spaced as far apart as every 8 hours.

Dosages of up to 1,600 mg of levodopa per day are enough for most people. But some people may need higher dosages. The maximum dosage is  2,400 mg of levodopa per day.

Carbidopa / levodopa ER also comes as a 25 mg/100 mg tablet. The different tablets can be combined to make up the desired daily dosage. If you’re taking multiple types of tablets, it’s best for the smaller doses to be given at the end of the day. This allows carbidopa / levodopa levels to be higher during the day, so that your PD symptoms are better controlled. 

For example, if your prescribed dosage is 1,000 mg of levodopa per day, you may take 400 mg levodopa twice a day and 200 mg levodopa once in the evening. Using the 50 mg/200 mg tablets, this may be prescribed as 2 tablets in the morning, 2 tablets in the afternoon, and 1 tablet in the evening.

Can you take IR and ER carbidopa / levodopa tablets together?

It’s possible to take IR and ER carbidopa / levodopa tables together. Taking carbidopa / levodopa ER alone may not be enough to control severe PD symptoms. In that case, IR tablets may be added to the ER tablets for some people who need more symptom relief. But this should only be done with careful instructions from a healthcare provider.

Can you switch from IR to ER carbidopa / levodopa tablets?

Yes, it’s possible to switch from IR to ER carbidopa / levodopa tablets. And it may be beneficial. ER tablets release levodopa in a more steady way than IR tablets do. And some people won’t have to take doses as frequently with ER tablets as they would with IR tablets (though, this isn’t always the case).

Keep in mind that carbidopa / levodopa IR and ER tablets aren’t absorbed the same way by the body. The body typically absorbs ER tablets more slowly, so you may not experience the effects for up to 1 after you take your first dose of the day. This is different from the IR tablets, which tend to work more quickly.

Below is a table that shows the usual dosage recommendations for switching from IR to ER tablets. The dosages are based on the levodopa component.

How should you take carbidopa / levodopa?

There are a few important tips to keep in mind when taking carbidopa / levodopa, including:

• Don’t crush or chew the tablets. Carbidopa / levodopa tablets shouldn’t be crushed or chewed. They should be swallowed whole or cut into half tablets if needed. The ODTs should be placed on the tongue to dissolve.

• Protect ODTs from moisture. ODTs should be handled with dry hands. They should only be removed from the bottle when it’s time for a dose. Don’t take them out of the bottle in advance.

•  Food can affect how well carbidopa / levodopa is absorbed. If you eat a lot of protein, your body may absorb less levodopa. While this doesn’t apply to everyone who eats a high-protein diet, if you’re noticing that carbidopa / levodopa isn’t working for you, talk to your healthcare provider. They can help determine if a high protein diet is the cause, and recommend ways to work around it if needed. For example, they may recommend that you keep your protein intake consistent throughout the day, so that your carbidopa / levodopa doses can be absorbed steadily.

• Iron supplements can lower carbidopa / levodopa levels. Iron supplements can lower levodopa absorption in the body. If you need iron supplements for a health condition, talk to your provider about how to manage this interaction. They may ask you to space out your iron supplements from your carbidopa / levodopa doses.

What happens if you miss a dose of carbidopa / levodopa?

If you miss a dose of carbidopa / levodopa, take the medication as soon as you remember. But if you remember when you’re already close to taking your next dose, skip the missed one.

Don’t take more than one carbidopa / levodopa dose at a time. Doubling up on doses can be dangerous and lead to more side effects, such as movement problems and mood changes.

What should you do if you take too much carbidopa / levodopa?

Taking too much carbidopa / levodopa can be dangerous and increase your risk of side effects. These side effects may include low blood pressure, a fast heartbeat, and confusion. If you’ve taken too much carbidopa / levodopa, seek emergency care or call Poison Control at 1-800-222-1222 right away.

How to save on carbidopa / levodopa

Carbidopa / levodopa IR and ER tablets are available as generic medications. GoodRx may be able to help you save over 50% off the average retail price of one of these generics. Generic IR carbidopa / levodopa at certain pharmacies may be as low as $9.00 with a free GoodRx coupon. Generic ER carbidopa / levodopa may be as low as $28.63.

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Written by:

Amy B. Gragnolati, PharmD, BCPS

Amy Gragnolati, PharmD, BCPS, is a pharmacy editor for GoodRx. Amy currently holds her pharmacist license in Georgia and California.

Reviewed by:

Christina Aungst, PharmD

Christina Aungst, PharmD, is a pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019, transitioning from freelance writer to editor in 2021.

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