Everyone gets the occasional when-will-this-day-end headache. These headaches may even follow a certain pattern. (Mine usually strike like clockwork if I miss my morning cup of French press coffee.)

But when is a headache cause for concern?

"Most bouts of regular headaches are not serious and can be treated on their own," says Dr. Elizabeth Loder, chief of the division of headache in the department of neurology at Harvard-affiliated Brigham and Women's Hospital. "However, being aware of the features of the different types of headaches can help you determine if your headaches are something more serious that requires medical attention."

Headache know-how

There are three main types of headache: tension, migraine, and cluster. Here is a look at each one.

Tension. This is the most common type of headache. A typical attack produces a dull, squeezing pain on both sides of the head like it's in a vise. The shoulders and neck can also ache. Episodes can last 30 minutes to seven days.

Although the cause of tension headaches is unknown, triggers include stress, fatigue, and lack of sleep.

The good news is that you can treat most tension headaches with over-the-counter (OTC) pain relievers, such as acetaminophen (Tylenol) or nonsteroidal anti-inflammatories, such as aspirin, naproxen (Aleve), or ibuprofen (Advil, Motrin). You could also try a warm shower, a nap, or a light snack.

Migraine. Migraines are more severe and can be quite debilitating. The pain often is centered on one side of the head, beginning around the eye and temple and spreading to the back of the head. Episodes can last from four to 72 hours.

According to Dr. Loder, one way to remember the features of a migraine is the acronym POUND:

P: pulsating pain
O: one-day duration of severe untreated attacks
U: unilateral (one-sided) pain
N: nausea and vomiting
D: disabling intensity.

Although migraines can strike without warning, they may be set off or worsened by specific triggers or aggravating factors, such as loud noises, a bright light, or strong smells. In some people, attacks are preceded by several hours of fatigue, depression, and irritability.

Almost a quarter of people with migraines often have an aura beforehand and experience halos, sparkles or flashing lights, and wavy lines. Numbness or tingling is also common. This often appears on one side of the body, usually in the face or hand.

If you catch a migraine early, you may be able to control it with an OTC pain reliever. If this doesn't help, or if your migraines become more frequent or severe, ask your doctor about a stronger prescription drug. Common options include triptans, such as rizatriptan (Maxalt), sumatriptan (Imitrex), and zolmitriptan (Zomig). These are available as tablets, nasal sprays, or injections that patients can give to themselves. Triptans often provide complete relief within two hours. Other medicines — and even botulism injections — may help, too.

Cluster. Cluster headaches strike five times more often in men than in women. This type of headache gets its name because they come in clusters; for example, one to eight headaches a day over a one-to-three-month period that may reoccur every few years.

The pain is quite severe and always strikes one side of the head. The headache begins abruptly and lasts for 30 minutes to an hour, on average. Also, the eye on the painful side tends to become red and watery, the eyelid often droops, and the nose gets runny. Most people become restless and agitated during an attack, and nausea and sensitivity to light and sound is common.

Unfortunately, OTC drugs usually don't offer much, if any, relief. High-dose oxygen can be effective if taken during the onset of pain. Several medications can help shorten the duration of attacks. For example, sumatriptan can often provide quick relief, especially when given by injection, but a nasal or oral triptan also may help. And an injectable medicine called galcanezumab (Emgality), used for migraine prevention, is now FDA-approved to reduce episodes of cluster headaches.

Other types of headaches

Headaches also can be caused by other conditions or situations. These are often short-lived and easily treated. For example:

Sinus headaches. A sinus infection can cause pain over the forehead, around the nose and eyes, over the cheeks, or in the upper teeth. When the infection resolves, the pain disappears.

Brain freezes. Some people develop a sharp, sudden headache when they eat or drink something cold. The pain usually goes away within a few minutes. If this is a common problem, try to warm the cold food at the front of your mouth before swallowing.

Exercise headaches. Strenuous exercise can sometimes trigger a headache. Make sure you are well hydrated before and after exercise. Taking an OTC anti-inflammatory beforehand also may help.

When to worry about a headache

Most headaches respond to self-care, OTC pain relievers, or medication your doctor prescribes. For some headaches, though, it's best to promptly seek medical advice. Warning signs include a headache that:

• is unusually severe or steadily worsens
• follows a blow to the head
• is accompanied by fever, stiff neck, confusion, decreased alertness or memory, or neurological symptoms such as visual disturbances, slurred speech, weakness, numbness, or seizures.

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