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What Are the Side Effects of Naproxen?

M.C. Huguelet
M.C. Huguelet

Naproxen is an anti-inflammatory drug used to temporarily reduce swelling and alleviate pain arising from various causes. While many people experience no noticeable side effects when taking naproxen, some individuals have uncomfortable or even dangerous reactions to the drug. Some side effects of naproxen, such as digestive upset, fatigue, and head pain, can be unpleasant, but may be less uncomfortable than the condition for which the drug is being taken. Conversely, certain symptoms may signal one of serious potential naproxen side effects, such as bleeding of the stomach, blood clots, liver failure, or anaphylaxis. Those experiencing symptoms of such side effects should seek immediate medical attention.

Should they occur, the side effects of naproxen are usually fairly minor. After taking the drug, some individuals experience mild fatigue and headaches. Others experience one or more digestive issues, including nausea, diarrhea, constipation, and vomiting. While such side effects can be unpleasant, they are often considered less uncomfortable than the pain or swelling for which naproxen is being taken. Some find that taking the drug with food can reduce the occurrence of minor side effects.

A packet of naproxen pills.
A packet of naproxen pills.

Conversely, some side effects of naproxen can indicate that a very serious reaction to the drug is taking place. In very rare cases, for instance, those taking naproxen may experience unusual digestive symptoms such as intense abdominal pain, black, grainy vomit, and very dark stools. These symptoms may indicate that naproxen is causing the stomach to bleed.

Abdominal pain can be a serious side effect of naproxen.
Abdominal pain can be a serious side effect of naproxen.

Very rarely, taking naproxen may lead to blood clots, which in turn can cause a heart attack or stroke. Those experiencing weakness confined to one side of the body or chest pain while taking naproxen may be suffering from a blood clot or another cardiovascular side effect. Such side effects most often occur in those with pre-existing cardiovascular issues.

Also among the serious potential side effects of naproxen is liver failure. One of the most common symptoms of this condition is yellowness of the whites of the eyes and the skin. Liver failure is also sometimes signaled by stomach pain, very dark urine, and chronic tiredness.

Another possible side effect of naproxen is anaphylaxis, or a severe allergic reaction which can lead to organ failure and death if left untreated. Classic symptoms of anaphylaxis include difficulty breathing, the emergence of hives on the skin, extreme itchiness, and swelling of the tongue and face. Those experiencing symptoms which may indicate serious naproxen side effects should seek medical attention immediately.

Discussion Comments


I just started taking these and they make me really tired.


My doctor doesn't believe me, but I'm sure that naproxen makes me gain weight. I have gained ten pounds in two weeks.


@burcidi-- You're absolutely right. Naproxen has a blood thinning effect. People who have issues with blood clogging or blood pressure should be careful when taking this medication. It may cause excessive blood loss in the event of a cut in the former and a drop in blood pressure in the latter.

This side effect from naproxen tends to go unnoticed because it's not as common as some of the other side effects like upset stomach and ulcers. Also, the higher the dose of the medication and the longer it is used, the higher the risk of these side effects.


Does naproxen thin out blood like aspirin?

I'm not too familiar with naproxen sodium side effects and I started using it recently for arthritis. I'm also a diabetic and noticed recently that when I prick my finger to do a blood glucose test, my blood is very thin and flows much more quickly than before. Aspirin has this effect on me, so I'm wondering if naproxen sodium is the same. Does anyone know?

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    • A packet of naproxen pills.
      A packet of naproxen pills.
    • Abdominal pain can be a serious side effect of naproxen.
      By: Africa Studio
      Abdominal pain can be a serious side effect of naproxen.